CN106103465B

CN106103465B - Immunoglobulin purification using a precleaning step

Info

Publication number: CN106103465B
Application number: CN201580012972.5A
Authority: CN
Inventors: F·费尔弗尔迪; Z·本科; M·加斯帕尔
Original assignee: Jirui Factory
Current assignee: Jirui Factory
Priority date: 2014-03-10
Filing date: 2015-03-09
Publication date: 2021-01-08
Anticipated expiration: 2035-03-09
Also published as: LT3116891T; CN106103465A; EP3116891B1; DK3116891T3; EP3674310A1; CA2930350A1; JP6293907B2; KR20160124107A; EP3116891A1; US20170058019A1; JP2017507907A; KR101921552B1; CA2930350C; ES2784749T3; SI3116891T1; PL3116891T3; US10487138B2; PT3116891T; HUE048782T2; WO2015135884A1

Abstract

The present invention relates to the purification of immunoglobulins and the problem of providing a method for purifying immunoglobulins in an efficient and cost-effective manner and in a satisfactory purity and yield. In particular, the present invention relates to the aspect of recycling of very costly chromatography materials, especially the lifetime of chromatography materials used for downstream process capture steps, and how the chromatography material lifetime can be increased while reducing the technical complexity of the purification process.

Description

Immunoglobulin purification using a precleaning step

Technical Field

The present invention relates to methods of purifying antibodies from cell culture derived compositions using a pre-wash step prior to the capture step and/or other polishing steps following the capture step.

Background

The selection of efficient and economical downstream sequences for purification of polypeptides produced by recombinant DNA techniques is an important step in the development of each new biopharmaceutical intended for therapeutic use. Recently, the need for large scale purification processes of monoclonal antibodies has further increased with the use of improved cell culture methods leading to higher cell densities and higher expression rates due to their exceptionally high therapeutic doses in medical use. Increasing product and contaminant concentrations in the culture broth place higher demands on the capture chromatography, on its preceding sample clarification step and on the subsequent polishing chromatography. The whole downstream process must: (i) treating the increased product amount; (ii) effective removal of added process-related and product-related impurities to below established acceptance criteria; and (iii) maintain economical yield and sufficient quality of mab. Typically, downstream processes account for a large portion of the total manufacturing cost of the therapeutic antibody.

Mab in the crude fraction is often bound to impurities such as Host Cell Proteins (HCP), host DNA, viruses, aggregates, other undesirable product variants and various leachates from process materials (leach). The presence of these impurities is a potential health risk for the patient, and thus regulations require that they be excluded from the final product. Only very low residual amounts can be tolerated.

The classical procedure for purification of cell culture derived polypeptides follows the sequence of capture chromatography-intermediate chromatography-polishing chromatography, with filtration, concentration or dialysis steps at various positions in the downstream sequence. In recent years, platform approaches have been successfully established in the field of mab purification. Since mabs are well-defined glycoprotein species with common physicochemical properties, it is reasonable to use the universal platform process (Kelly B2009). This general process (with more or less product-specific modifications) can be applied to many mabs, especially those immunoglobulins belonging to the same class or subclass (e.g., IgG 1).

One of the most common capture steps for mab purification is protein a affinity chromatography. This capture provides excellent selectivity for Fc-containing molecules, thereby removing over 99.5% of contaminants in a single step. However, in addition to its advantages, two disadvantages should be mentioned. One disadvantage is the undesirable leaching of protein a or protein a fragments, which are known to be toxic (Gagnon P1996). Another disadvantage is the high cost of such resins, especially on an industrial scale necessary for the purification of therapeutic antibodies. Protein a resins are approximately 30 times more expensive than ion exchange resins. Calculated for 10m³Downstream processing of cell cultures, protein a affinity chromatography costs approximately $ 4-5 million (Farid SS 2009).

Many solutions have been disclosed to overcome the problem of leaching protein A (Gagnon P1996; Fahrner RL 2001). Several methods involve a protein a post-chromatography step to remove leached protein a, such as anion exchange chromatography, cation exchange chromatography (WO2009058812), hydrophobic interaction chromatography (WO9522389), or a combination of chromatography, used in binding mode (EP0345549) or flow-through mode (WO2004076485), such as ion exchange chromatography followed by hydrophobic interaction chromatography (WO2010141039), anion exchange chromatography followed by cation exchange chromatography (WO2011090720), or cation exchange chromatography and mixed mode chromatography in either order (WO 2011150110). Due to the extremely high overall purity required for therapeutic antibodies, typical platform purification protocols include at least two steps of protein a post-chromatography, which is typically selected from cation exchange, flow-through mode anion exchange in flow-through, and hydrophobic interaction chromatography (Fahrner RL 2001, Kelly B2009, WO9522389, WO2009138484, WO2010141039, WO2011017514, WO 2011090720).

Other methods have reduced the leachables during protein a affinity chromatography by using a special wash to remove the leached protein a prior to elution of the immunoglobulin. A number of intermediate wash buffers were developed which contain salts or other components, for example hydrophobic electrolytes such as tetramethylammonium chloride (Fahrner RL 2001).

Some methods work closer to the source of protein a leaching by directly reducing the proteolytic activity originating from the sample. Most protein a leaching is caused by proteolysis. This reduced leaching is achieved by low temperature and/or by adding protease inhibitors to the buffer (WO 2005016968).

Particular methods for avoiding or reducing leaching of protein a include pre-treatment of protein a resins with surface active compounds, for example chaotropic substances such as urea or guanidine hydrochloride (WO 03041859).

It has long been known that different types of protein A resins exhibit different degrees of leaching (Faglistaller P1989). Therefore, the choice of protein a material is an important factor. In addition to the ligand itself, the matrix also influences the leaching, binding capacity (binding capacity) and flow rate (Fahrner RL 2001). These parameters together determine column size, process time and thus the economics of the affinity capture step. In addition, over the past decade, chromatography suppliers developed natural golden yellow grape by genetic engineeringStaphylococcal (Staphylococcus aureus) protein A sequences provide more robust protein A ligands. These improved resins comprise a rigid matrix in combination with an improved recombinant ligand protein specifically engineered to be alkali tolerant, have high binding loads, and low ligand leakage. An example is MabSelect SuRe from GE Healthcare Life Sciences^TM(WO 2009138484). This material can be washed quickly and efficiently after operation with up to 0.5M NaOH. However, these benefits come at a cost. MabSelect SuRe and comparable modern resins are significantly more expensive than previous generation protein a resins. Thus, despite these new affinity media, there is no economic benefit, and the opposite is true.

In view of the very high costs associated with protein a-based affinity capture, it is not surprising to develop alternative strategies that completely avoid immunoglobulin purification by any affinity chromatography. An example is the use of high performance tangential flow filtration in combination with non-affinity chromatography such as anion exchange chromatography, cation exchange chromatography, hydrophobic interaction chromatography or mixed mode chromatography (WO 03102132).

In many cases, the capture step is performed with a coarse input (loading) material, which can lead to contamination of the affinity column resin (impurities accumulate on the affinity column resin). This can prevent successful reuse of the capture resin in the absence of an appropriate regeneration step. In the case of protein a affinity capture, it must be emphasized that ligand leaching is not a major factor limiting the lifetime of protein a resins. Contaminants in the crude broth (such as lipids, oxidants, aggregates or particulates, metal ions and other substances) contribute to resin contamination (fouling). In addition to direct effects on the protein a binding moiety, the matrix may also be irreversibly contaminated. The result is a reduction in load and flow rate from run to run. This problem is not limited to protein a resins: contamination of chromatography resins over their operating life is a significant problem prevalent in commercial bioseparations. Hydrophobic ligands used for hydrophobic interaction chromatography and mixed mode chromatography are particularly prone to entrap lipophilic contaminants from the culture broth when used as a capture step for cell culture derived immunoglobulins. Although there is a complex flow of post-run wash steps, the lifetime of the trap column is limited and depends on the number of cycles, the operating conditions of run and wash, and the purity of the sample.

Mixed mode chromatography is mainly described as the choice for the downstream purification step of protein a (Kelly, b.2009, WO 03102132). Use of Capto MMC in known binding mode for purification of mab. Special elution conditions were developed (WO 2011049798). Likewise, CaptoAdhere, preferably in flow-through mode, has been shown to be a suitable purification step after flow-through anion exchange chromatography followed by protein a affinity chromatography (WO 2013066707). Furthermore, several different mixed mode resins were investigated in overload and elution chromatography mode, captoaphere being most preferred (WO 2013067301).

To clarify the heavily contaminated culture broth, a mechanical separation step is utilized which removes most of the cell debris and aggregates. Centrifugation and filtration are the most common pre-treatment steps performed prior to loading the sample onto the capture resin. For large volumes, centrifugation is performed through a cell separator and a filtration step is performed through a depth filter and/or a microfilter. The resulting culture broth was referred to as "clarified cell culture supernatant" (Liu HF 2010). While direct loading of harvest broth onto protein a resin is a common method option (Fahrner RL 2001), other platform technologies utilize clarification steps, i.e., centrifugation, depth filtration and/or microfiltration (Liu HF 2010, WO9522389, WO2001150110), to protect the capture column.

Pre-wash chromatography steps performed alternatively or additionally on the basis of centrifugation/filtration are only sporadically reported. Immobilized metal (Zn2+) chelate chromatography (IMAC) was used on a very small scale before protein a (VanDamme a. -m.1990, bullets f.1991). In contrast, weak anion exchange chromatography on DEAE Cellulose was used after centrifugation, filtration and concentration, and the flow-through obtained was then loaded onto protein a (EP 0550400). Finally, the advantage of pre-treating the broth with depth filtration prior to protein a was examined and compared to flow-through mode anion exchange chromatography on less efficient TMAE Fractogel (Yigsaw Y2006).

Summary of The Invention

Conventional downstream chromatographic processes for purifying immunoglobulins from cell culture fluids typically begin with a capture chromatography step, wherein the immunoglobulins must be captured from a sample containing the immunoglobulins together with impurities. The immunoglobulins are separated from the impurities substantially due to selective binding of the immunoglobulins to the capture chromatography resin, the impurities are not bound to the resin and are thus obtained in the flow-through, whereas the immunoglobulins are obtained in the eluate.

This capture chromatography step is typically the most expensive step in immunoglobulin purification, accounting for 40 to 50% of the overall downstream process costs. The cost of the capture step is particularly high when protein a affinity chromatography is used. The same applies to mixed mode chromatography columns, which may alternatively be used as capture chromatography steps in immunoglobulin purification.

There is a continuing need for cost-effective purification of immunoglobulins from large volumes of cell culture and fermentation broths, and from samples derived from such cell culture or fermentation broths. In particular, there is a need for a purification process that is cost effective while still being efficient and satisfactory in purity and yield.

It has been found that by incorporating an additional chromatography step upstream of the capture chromatography step, the overall cost of the purification process can be significantly reduced. The additional chromatography step upstream of the capture chromatography step reduces the impurity loading to which the high cost capture chromatography material is exposed. This so-called "pre-wash" step is performed with a chromatography material that is less expensive and more durable and easily regenerated than the chromatography material used in the subsequent capture step.

In order to keep the purification process as simple as possible, in a preferred embodiment the pre-washing step is performed in flow-through mode, i.e. the immunoglobulin to be purified is not bound to the resin and thus obtained in the flow-through fraction, whereas the impurities remain largely on the resin and are thus separated from the immunoglobulin.

In another preferred embodiment, the pre-wash step and the capture step are connected in series, so that the flow-through of the pre-wash step is not temporarily stored in the collection vessel, but is immediately transferred to the capture chromatography resin.

In order to achieve the high purity required for immunoglobulins intended for therapeutic use, after the pre-wash step and the capture chromatography step, one or more chromatographic polishing steps are performed after the capture chromatography step.

The problem underlying the present invention is solved by providing a method for purifying an immunoglobulin from a sample comprising the immunoglobulin and at least one impurity, the method comprising the following steps in the following order:

(a) exposing the sample to anion exchange chromatography to obtain immunoglobulins in the flow-through that do not bind to the anion exchange chromatography resin;

(b) exposing the flow-through obtained in step (a) to protein a affinity chromatography, wherein the immunoglobulin binds to the protein a affinity chromatography resin, obtaining the immunoglobulin in the eluate by eluting the protein from the protein a affinity chromatography resin; or exposing the flow-through obtained in step (a) to mixed mode chromatography, wherein the immunoglobulin binds to the mixed mode chromatography resin and the immunoglobulin is obtained in the eluate by eluting the protein from the mixed mode chromatography resin;

(c) exposing the eluate obtained in step (b), or a composition derived therefrom and obtained after one or more further processing steps performed after step (b), to cation exchange chromatography, wherein the immunoglobulin is bound to the cation exchange chromatography resin, and obtaining the immunoglobulin in the eluate by eluting the protein from the cation exchange chromatography resin.

The present invention further solves the problem of increasing viral safety in immunoglobulin manufacturing processes.

Brief Description of Drawings

FIG. 1: process protocols for conventional immunoglobulin purification methods

FIG. 1A shows a general process scheme for purification of immunoglobulins from large volume cell cultures. Starting from a clarified bulk material obtained after centrifugation and/or filtration of the harvested culture broth, the process comprises a protein a capture step and two subsequent refining steps. This protocol includes two typical viral security steps. The virus inactivation step is performed by keeping the protein a eluate at a low pH and the nanofiltration step for virus removal is performed after the last purification step. The final step is usually tangential flow ultrafiltration and/or diafiltration (UF/DF-TFF) to set the desired immunoglobulin concentration and concentration of formulation ingredients.

Fig. 1B shows a classical process scheme including three-step chromatography (e.g., as per Fahrner r.l.2001 or Kelly b.2009) for purification of immunoglobulins from large-volume cell cultures. This process is the same as that in FIG. 1A except that the disclosed purification step is cation exchange chromatography (purification step 1) followed by anion exchange chromatography (purification step 2). It must be emphasized that cation exchange chromatography is carried out in binding mode, whereas anion exchange chromatography is carried out in flow-through mode. It should be mentioned that a common equivalent variant of this classical scheme is simply to change the order of the refining steps 1 and 2.

FIG. 2: exemplary Process protocols for use with Pre-clean step of the invention

Figure 2A shows a large scale process scheme with a pre-wash step prior to the protein a capture step. The harvested cell culture was clarified by preparative centrifugation using a separator followed by depth filtration and microfiltration. The pre-wash chromatography step is performed by using an anion exchange column in flow-through mode. In a preferred configuration, the precleaned column is directly connected to the protein a capture chromatography column. The two purification steps are cation exchange chromatography (purification step 1) and then mixed mode chromatography (purification step 2) using bind and elute modes. Mixed mode resins have positively charged ligands and can be carried out in binding mode or in flow-through mode. This second refining step is optional. The viral safety steps and the final UF/DF-TFF are depicted in FIG. 1A.

Figure 2B shows an alternative large-scale process scheme similar to that of figure 2A, except that another mixed mode chromatography is inserted between the prewash anion exchange and protein a affinity chromatography. This mixed mode chromatography is performed with a resin containing negatively charged ligands (e.g., Capto MMC) or with a resin containing positively charged or uncharged ligands (e.g., MEP HyperCel), and is performed in binding mode. Thus, mixed mode chromatography functions as a capture step in this process, whereas protein a affinity chromatography is better defined as an intermediate step within this protocol. The second mixed mode chromatography step, which is the last step of chromatography, is optional. All other steps are as described below in fig. 2A.

Figure 2C shows another alternative large scale process scheme similar to the process of figure 2A, except that mixed mode capture chromatography is substituted for protein a capture chromatography. This mixed mode chromatography is performed with a resin containing negatively charged ligands (e.g., Capto MMC) or with a resin containing positively charged or uncharged ligands (e.g., MEP HyperCel), and is performed in binding mode. Unlike the process shown in fig. 2B, this process lacks protein a affinity chromatography. All other steps are as described below in fig. 2A.

Detailed Description

As used herein, a "sample" or "sample comprising an immunoglobulin and at least one impurity" comprises an immunoglobulin of interest and at least one impurity. The sample may be obtained directly from a host cell or organism that produces the immunoglobulin. The sample may be harvested cell culture fluid, cell culture supernatant or pre-treated cell culture supernatant. The sample may be partially clarified or purified by centrifugation and/or filtration (e.g., microfiltration, diafiltration, ultrafiltration, and depth filtration).

The term "pre-treated sample" as used herein is, for example, a cell culture supernatant prepared for a chromatography step used in the method of the invention, e.g., to adjust the pH and/or conductivity range and/or buffering capacity to achieve the desired chromatographic performance and to stabilize immunoglobulins, the sample is subjected to one or more adjustments including buffer exchange, dilution, addition of salts, detergents, chaotropic substances or organic compounds, pH titration or filtration. Since immunoglobulins expressed from mammalian cells are normally secreted into the cell culture broth during the culture process, product collection is performed by separating the cell culture broth from the cells at the end of the culture process. The cell separation method should be gentle to minimize cell disruption to avoid the increase of cell debris and the release of proteases and other molecules that may affect the quality of the immunoglobulin product. Typically, the harvest from mammalian cell cultures is centrifuged and then filtered. Expanded bed adsorption chromatography is an alternative method to avoid the centrifugation/filtration method. Other sample processing prior to purification by chromatographic steps may be concentration and/or diafiltration of the cell culture supernatant to specific immunoglobulin concentrations, pH ranges, conductivities and buffer species concentrations.

The terms "impurity" and "contaminant" are used interchangeably herein to refer to any substance that is different from the immunoglobulin of interest. Examples may be cell culture media components, host cell proteins, endotoxins, viruses, lipids, DNA, RNA, extracts from process materials, and aggregates or fragments thereof. Aggregates, charge variants, misfolded molecules or fragments of the immunoglobulin of interest to be purified are also considered as impurities.

The term "chromatography medium" as used herein must be understood as a chromatography material or medium in the form of beads, plates, crystals, monolith, membranes, fibers, fiber mesh, or any other solid phase. The "mediator" has functional groups called "ligands" that bind to a backbone called the "matrix". One exception is gel chromatography resins for size exclusion chromatography, which generally do not contain any attached ligands. Thus, the term "medium" does not limit the process of the invention to only column chromatography using chromatography resins, but also includes other types of chromatography, such as membrane chromatography using membrane adsorbents. Specifically, in anion exchange chromatography, both an anion exchange resin or an anion exchange chromatography membrane are included in the present invention.

"resin" refers to any chromatographic material or medium in the form of beads comprising a matrix having binding functional groups (ligands) that can interact with a protein or at least one contaminant. One exception is gel chromatography resins for size exclusion chromatography, which generally do not contain any attached ligands. The resin may be provided as pellets of different sizes and packed in a column. Alternatively, pre-packed columns may be purchased.

The term "binding mode" or "binding and elution mode" refers to a chromatography condition wherein a sample containing the immunoglobulin to be purified is applied to a chromatography column wherein the immunoglobulin is bound to a chromatography medium. Thus, the immunoglobulins remain on the chromatographic medium, whereas impurities of the sample may be present in the non-binding fraction (also called flow-through fraction). Where the chromatography step is performed in binding mode, one or more washing steps may be performed after the immunoglobulin has bound to the chromatography medium and before the immunoglobulin is eluted from the medium. To obtain the immunoglobulin, it is then eluted and obtained in the eluate, which may then be further purified in further chromatography steps as required. Elution of the immunoglobulin may be performed with selective conditions that allow the contaminants to remain bound to the medium while the immunoglobulin elutes.

Performing the chromatography step in "binding mode" does not necessarily mean binding 100% of the immunoglobulin of interest. In the context of the present invention, "binding chromatography resin" or "binding chromatography medium" refers to an immunoglobulin binding resin or medium that is at least 50% immunoglobulin bound, preferably at least 75% immunoglobulin bound, more preferably at least 85% immunoglobin bound, most preferably more than 95%.

The terms "flow-through mode", "obtaining immunoglobulins in the flow-through which do not bind to the chromatography resin" and "obtaining immunoglobulins in the flow-through which do not bind to the chromatography medium" refer to chromatography conditions, wherein a sample containing the immunoglobulin of interest is added to the chromatography resin or medium, wherein the immunoglobulin does not bind to the chromatography resin but is predominantly present in a fraction which does not bind to the resin or medium and is thus comprised in the flow-through.

Performing the chromatography step in "flow-through mode" does not necessarily mean that 100% of the immunoglobulins of interest do not bind and are therefore comprised in the flow-through. In the context of the present invention, "does not bind to the chromatography resin" or "does not bind to the chromatography medium" means that at least 50% of the immunoglobulins do not bind, preferably at least 75% of the immunoglobulins do not bind, more preferably at least 85% of the immunoglobulins do not bind, most preferably more than 95% of the immunoglobulins do not bind to the resin or medium. The impurities may be bound to the resin or media in this manner.

In the context of the present invention, it is understood that the precleaning chromatography step of the present invention is performed in flow-through mode, while the capture step is considered to be the first chromatography step, which is performed in binding mode.

In the experiments leading to the present invention it was observed that the cell-free harvest material (clarified supernatant) still contains several substances that strongly bind to the capture resin together with the immunoglobulin to be purified. This affects the reuse of the resin. According to the findings of the present invention, insertion of a suitable pre-wash column represents a good solution for rapid purification of additional clarified broth. By combining with other impurities, the pre-wash column improves sample purity, reduces key contaminants, and protects high cost affinity columns. The precleaned column should be reusable and its regeneration should be possible by simple means. Most suitable are strong anion exchange chromatography media having a robust matrix with ligands selected from quaternary aminoethyl, quaternary ammonium, or trimethylammonium moieties, e.g., as provided by Nuvia Q. The use of a pre-washed anion exchange column in flow-through mode has several advantages: the column can be kept relatively small and it can be directly connected to the capture column. This configuration avoids the temporary collection and storage of anion exchange eluate, reduces the number of steps, and improves the economics of the process. The anion exchange column may be followed by protein A or mixed mode resins (e.g., Bakerbond ABx, Capto MMC, Capto Adhere, or MEP HyperCel) or any other high-priced resin that is difficult to regenerate.

The term "in the following order" is understood to mean that the process steps mentioned are carried out in the order listed. Other process steps may be incorporated before, after, and between the listed process steps.

The present invention provides a method for purifying an immunoglobulin from a sample comprising the immunoglobulin and at least one impurity, the method comprising the following steps in the following order:

(b) exposing the flow-through obtained in step (a) to an immunoglobulin-binding protein/peptide affinity chromatography, wherein the immunoglobulin binds to the immunoglobulin-binding protein/peptide affinity chromatography resin, obtaining the immunoglobulin in the eluate by eluting the protein from the immunoglobulin-binding protein/peptide affinity chromatography resin; or exposing the flow-through obtained in step (a) to mixed mode chromatography, wherein the immunoglobulin binds to the mixed mode chromatography resin and the immunoglobulin is obtained in the eluate by eluting the protein from the mixed mode chromatography resin;

(a) exposing the sample to anion exchange chromatography to obtain immunoglobulins that do not bind to the anion exchange medium in the flow-through;

The term "other processing steps" refers to any step commonly applied within a protein purification scheme, such as filtration, dialysis, viral inactivation, dilution, concentration, pH adjustment, conductivity adjustment, or intermediate chromatography steps. Other processing steps may be applied between all chromatography steps of the invention. In addition to the step (a) of exposing the sample to anion exchange chromatography and the step (b) of exposing the flow-through obtained in step (a) to chromatography, an intermediate chromatography step may be applied between any chromatography steps. In particular, the term "further processing step" refers to an intermediate chromatography step applied between capture chromatography and cation exchange chromatography. The intermediate chromatography step may be performed with any chromatography medium. The intermediate chromatography step may utilize any type of chromatography, including column chromatography and membrane chromatography.

In one embodiment, no further treatment step is applied between exposing the sample to anion exchange chromatography of step (a) and exposing the flow-through obtained in step (a) to chromatography of step (b).

In another embodiment, no filtration, e.g. sterile filtration, is applied between exposing the sample to anion exchange chromatography of step (a) and exposing the flow-through obtained in step (a) to chromatography of step (b).

A pre-cleaning step: anion exchange chromatography

The method of the invention involves a flow-through mode anion exchange chromatography step as a pre-wash step prior to the capture step. The anion exchange chromatography medium may be a strong or weak anion exchange chromatography medium, including an anion exchange membrane.

This pre-wash anion exchange chromatography step has been found to be effective in retaining impurities that might otherwise cause precipitation at acidic pH, and bind host nucleic acid molecules, such as DNA and RNA. It was also found that substances from the crude sample that promote the contamination of the chromatographic capture column were pre-captured by the pre-wash anion exchange column, avoiding access to the subsequent capture column.

In addition, the pre-wash step has a significant effect on protein a leaching, which can be greatly reduced by using pre-wash chromatography.

Finally, it was observed that in case precipitation and/or turbidity was observed during the protein a eluate holding step for virus inactivation, this effect could be completely avoided when using pre-wash anion exchange chromatography. Since the chromatography medium of the pre-wash step is exposed to the highest impurity loading in the chromatography process, the chromatography medium of the pre-wash step requires a rapid, inexpensive and efficient regeneration and washing method. It has been found that regeneration of anion exchange chromatography media (e.g., resins or membranes) can be effectively performed in a rapid, inexpensive, and efficient procedure that includes only a few steps. For regeneration of the anion exchange chromatography medium, harsh conditions may be utilized that allow the chromatography medium to be washed in a short time without loss of function. Ion exchange chromatography relies on charge-charge interactions between the molecules to be bound and the charge immobilized on a matrix. In anion exchange chromatography, the molecules to be bound are negatively charged and the immobilized functional groups (ligands) are positively charged. Commonly used anion exchange chromatography media are Q media (quaternary amine ligands), TMAE resin (trimethylaminoethyl ligands) and DEAE resin (diethylaminoethyl ligands). In general, however, the anion exchange chromatography step can be carried out with all customary commercially available anion exchange media. The anion exchange medium can be used in the form of a pre-packed column or as a membrane. Alternatively, the resin may be purchased as a raw material and loaded into the column by the user. With respect to the capacity and size of the column, there is no particular limitation except for the conventional one. The skilled person will know the amount of anion exchange chromatography medium to be used and the size of the column. Depending on the overall scale of the process.

Typical strong anion exchange chromatography media useful for the purposes of the present invention comprise functional groups such as: quaternary Aminoethyl (QAE) moieties, including resins such as Toyopearl QAE (available from Tosoh Bioscience, germany), Selectacel QAE (a quaternary aminoethyl derivative of cellulose, available from Polysciences inc., Pennsylvania USA), QAE Sephadex (available from GE Healthcare, germany), and the like; quaternary ammonium (Q) moieties, resins include, for example, Q Sepharose XL, Q Sepharose FF, Q Sepharose HP, Q Sepharose CL-4B, Q Sepharose Big Beads, Source Q, Resource Q, Capto Q impress (all available from GE Healthcare, germany), Poros HQ (Applied Biosystems, germany), Q HyperCel, Biosepra Q Ceramic HyperD (available from Pall, New York, USA), Macro Prep High Q (Bio-Rad, ifcalornia, USA), Toyopearl Super Q (available from Tosoh Bioscience, germany), UNOsphere Q (available from Bio-Rad, California, USA); trimethylaminoethyl (TMAE) includes, for example, Fractogel EMD TMAE (Merck KgaA, Germany); trimethylammonium resins include, for example, Nuvia Q (available from Bio-Rad, California, USA).

In particular, strong anion exchange chromatography media have been found to be effective in retaining impurities and binding host nucleic acid molecules (such as DNA and RNA) that would otherwise cause precipitation at acidic pH.

Preferably, a strong anion exchange chromatography medium is used that comprises a ligand selected from the group consisting of Quaternary Aminoethyl (QAE) moieties, quaternary ammonium moieties, and trimethylammonium moieties other than trimethylammonium ethyl bound to a methacrylic acid polymeric matrix.

More preferably, the anion exchange chromatography may be strong anion exchange chromatography using a chromatographic column having N (CH)₃)₃ ⁺(Trimethylammonium; Nuvia Q, available from Bio-Rad, California, USA) functional groups (ligands) or media with similar characteristics.

Accordingly, a preferred embodiment of the present invention provides a method for purifying an immunoglobulin from a sample comprising the immunoglobulin and at least one impurity, the method comprising the following steps in the following order:

(a) exposing the sample to strong anion exchange chromatography to obtain immunoglobulins in the flow-through that do not bind to the strong anion exchange chromatography resin;

Chemical stability

1.0M NaOH (20 ℃ C.): at most 1 week

1.0M HCl (20 ℃ C.): at most 5 weeks

Gel bed compression ratio: 1.10-1.15 (settled bed volume/packed bed volume)

Stability of pH

In a preferred embodiment, the diameter of the pre-wash anion exchange column is greater than the diameter of the capture column. In another preferred embodiment, the bed height of the prewashed anion exchange column is shorter than the bed height of the trap column. In the most preferred embodiment, the diameter of the prewash column is greater than the diameter of the trap column and the bed height of the prewash anion exchange column is shorter than the bed height of the trap column. For optimal capture of impurities, a minimum of about 10cm of pre-wash anion exchange column height is required.

Some types of impurities may bind to the medium not only through ionic interactions but also through hydrophobic interactions. Complex formation may also occur. Since the precleaning chromatography step acts as a filter for undesirable contaminants that are tightly adsorbed to the media, it is necessary to develop an effective regeneration and cleaning process. For chromatography from strong anion exchange resins (e.g., having a-N (CH)₃)³⁺Ligands such as Nuvia Q) remove most of the impurities and the following regeneration methods (clean in place) can be used in the following order after their use: (a) solution A: 40mM sodium phosphate, 2M urea, 1.5M NaCl, 10mM EDTA, pH 7-8; (b) solution B: 2M NaCl, 100mM citric acid; (c) solution C: water; and (D) solution D: 1M NaOH; (e) solution E: 10mM NaOH. Solutions A-E were passed successively through the column. Solution E is available for storage. Regeneration in countercurrent is recommended.

Preferably, the pre-wash column and the capture step column may be in series. This means that the flow-through of the pre-wash step is not temporarily stored in the collection vessel, but is immediately transferred to the capture chromatography column. In a preferred method, both columns are disconnected after operation and regenerated separately (cleaned in place). The most preferred regeneration step is carried out in countercurrent.

Step of Capture

The term "capture step" is understood to mean the first chromatography step carried out in binding mode. The capture step for purification of immunoglobulins from the culture broth is usually performed as an affinity chromatography step. Protein a or its derivatives are mainly used as affinity capture. However, other chromatographic principles may be used as the capture step. According to the present invention, mixed mode chromatography can be successfully used to capture immunoglobulins.

In a preferred embodiment, the present invention provides a method for purifying an immunoglobulin from a sample comprising the immunoglobulin and at least one impurity, the method comprising the following steps in the following order:

(b) exposing the flow-through obtained in step (a) to protein a affinity chromatography, wherein the immunoglobulin binds to the protein a affinity chromatography resin, obtaining the immunoglobulin in the eluate by eluting the protein from the protein a affinity chromatography resin;

(b) exposing the flow-through obtained in step (a) to an immunoglobulin-binding protein/peptide affinity chromatography, wherein the immunoglobulin binds to the immunoglobulin-binding protein/peptide affinity chromatography resin, obtaining the immunoglobulin in the eluate by eluting the protein from the immunoglobulin-binding protein/peptide affinity chromatography resin;

In another preferred embodiment, the present invention provides a method for purifying an immunoglobulin from a sample comprising the immunoglobulin and at least one impurity, the method comprising the following steps in the following order:

(c) exposing the eluate obtained in step (b) or a composition derived therefrom and obtained after one or more further processing steps performed after step (b), obtaining immunoglobulins in the eluate by eluting the protein from the cation exchange chromatography resin.

(a) exposing the sample to strong anion exchange chromatography to obtain immunoglobulins in the flow-through that do not bind to the strong anion exchange chromatography resin of which the ligand is-N (CH)₃)₃ ⁺；

Protein A affinity chromatography

By using a protein a affinity chromatography step as a capture step after an anion exchange precleaning chromatography step, the method of the invention provides a cost-effective immunoglobulin purification method while taking advantage of the significant binding specificity of protein a affinity chromatography in immunoglobulin purification.

The term "immunoglobulin-binding protein/peptide affinity chromatography" as used herein refers to affinity chromatography using, as a ligand, a recombinant protein of microbial origin (e.g., staphylococcus aureus, Streptococcus (Streptococcus), Streptococcus magnus) or a variant derived therefrom or a synthetic peptide of microbial origin having the ability to bind immunoglobulins. Exemplary immunoglobulin-binding proteins may be protein A, protein G, protein L, or protein A/G. Preferably, the immunoglobulin-binding protein or peptide is protein a. The ligand may comprise one or more of the E, D, A, B and C domains of protein a. More preferably, the ligand comprises domain B of protein a or an engineered Z protein. An exemplary resin utilizing a 14kD peptide recombinantly produced with Saccharomyces cerevisiae as the ligand is IgSelect (GE healthcare). This ligand, available without further information, was specifically designed for high affinity to all types of human Fc.

In order to prepare protein a affinity chromatography materials with higher resistance to harsh wash conditions and to provide protection against cross-contamination effects between runs, it is now common to use modified protein a affinity resins with ligands specifically engineered to ensure alkali tolerance, high binding loading and low ligand leakage. However, one major disadvantage of these improved resins is that they are significantly more expensive than conventional protein a resins. An important advantage of the method of the invention is that both conventional protein a resins as well as more recent new generation protein a resin products can be used. As protein a resins are exposed to lower impurity loads, conventional and cheaper protein a resins become acceptable, although they are limited to milder regeneration conditions. However, due to the pre-wash step of the present invention, and independently of the protein a resin selected, both conventional and new generation resins can be used over a longer lifetime. Furthermore, the process becomes more economical as the washing of the protein a column becomes easier to implement.

Examples of common Protein A resins that can be used for the purposes of the present invention may include, but are not limited to, Unopshere SUPrA (Bio-Rad), Protein A Ceramic HyperD F (Pall Corporation), Poros MabApure A (Applied Biosystems), ProSep HC, ProSep Ultra and ProSep Ultra Plus (EMD Millipore), Protein A Sepharose FF, rProtein A Sepharose FF, rmp Protein A Sepharose FF, MAbSelect SuRe LX and MabSelect Xtra (GE Healthcare), and Toyopearl rProtein A (Tosoh Bioscience).

As used herein, the term "protein a" encompasses protein a recovered from its natural source, synthetically or biosynthetically produced protein a (e.g., by peptide synthesis or by recombinant techniques), and variants thereof that retain the ability to bind to proteins having the CH2/CH3 region. Preferably, resins with high incorporation loadings and/or base stability can be used. For example, protein a derivatives, alkali-stable protein a-derived affinity media (e.coli) may be used. Preferably, the protein A derived (E.coli) ligand is stabilized using an alkali. The alkali stable protein a derivative ligand may be coupled to a highly cross-linked agarose matrix, preferably fixed with a chemically stable thioether bond. One example is MabSelect SuRe from GE Healthcare Life Sciences, which can be quickly and efficiently washed with up to 0.5M NaOH after the run. The alkali stable ligand of MabSelect SuRe was derived from the B domain of protein a, essentially lacking the VH3 binding domain that provides higher elution pH. A preferred product is MabSelect SuRe LX, which has a higher binding capacity than MabSelect SuRe.

The protein a resin MabSelect SuRe LX was characterized as follows:

one or several washing steps with one or more special washing buffers may be included between protein a affinity chromatography and elution of the immunoglobulin from the protein a column. The wash buffer is a buffer used to remove impurities from the protein a resin without removing a significant amount of the immunoglobulin of interest bound to protein a. The wash buffer may comprise salts and detergents (e.g., polysorbates); salts and solvents (e.g., hexylene glycol); high concentration salts (e.g., high molarity Tris buffer); or salts and polymers (e.g., polyethylene glycol). Furthermore, the wash buffer may comprise a chaotropic agent (e.g. urea or arginine) and/or a protease inhibitor (e.g. EDTA).

For elution of the immunoglobulin of interest from the protein a column, an elution buffer is applied. Preferably, the elution buffer has a low pH, such thatThe interaction between protein a and the immunoglobulin of interest is disrupted by altering the protein conformation. Preferably, the low pH elution buffer has a pH in the range of from about 2 to about 5, most preferably in the range of from about 3 to about 4. Examples of buffers to control the pH within this range include phosphoric acid, acetic acid, citric acid, glycine, and ammonium buffers, and combinations of these. Such preferred buffers are citric acid and acetic acid buffers, most preferably sodium citrate or sodium acetate buffers. Other elution buffers are contemplated for eluting the immunoglobulin of interest, including high pH buffers (e.g., those having a pH of 9 or higher) or containing a ligand such as MgCI₂(2mM) buffer of the compound or composition.

Protein a affinity chromatography resin can be regenerated with 0.1 to 0.5NaOH, preferably in a column (wash in place).

In a specific embodiment, the present invention provides a method for purifying an immunoglobulin from a sample comprising the immunoglobulin and at least one impurity, the method comprising the following steps in the following order:

(b) exposing the flow-through obtained in step (a) to protein a affinity chromatography, wherein the immunoglobulin binds to a protein a affinity chromatography resin, obtaining the immunoglobulin in the eluate by eluting the protein from the protein a affinity chromatography resin, wherein the ligand of the protein a affinity chromatography resin is an alkali stable protein a derivative (e.g. MabSelect SuRe);

In another embodiment, the present invention provides a method for purifying an immunoglobulin from a sample comprising the immunoglobulin and at least one impurity, the method comprising the following steps in the following order:

Mixed mode chromatography as a capture step

(b) exposing the flow-through obtained in step (a) to mixed mode chromatography, wherein the immunoglobulin binds to the mixed mode chromatography resin, obtaining the immunoglobulin in the eluate by eluting the protein from the mixed mode chromatography resin;

Mixed Mode Chromatography (MMC) utilizes more than one form of interaction between a ligand and a sample molecule. Resins known as mixed mode resins are chromatography materials having functional groups comprising charged hydrophobic ion exchange ligands or crystalline minerals such as hydroxyapatite. The term "multimodal chromatography" or "hydrophobic charge induction chromatography" is sometimes used in place of "mixed mode chromatography". Mixed mode chromatography is generally an interplay of at least two principles: hydrophobic interaction and ion exchange or metal affinity interaction and ion exchange. Mixed mode chromatography offers less predictable selectivity, which cannot be reproduced by single mode chromatography methods such as ion exchange or hydrophobic interaction chromatography, respectively. The positively charged hydrophobic ligands belong to a group of mixed anion exchange modes (e.g. Capto MMC) and the negatively charged ligands belong to mixed cation exchange modes (e.g. captoaphere). Some mixed mode resins have zwitterionic character (e.g., Bakerbond ABx). Other mixed mode resins have hydrophobic ligands that can be ionized and converted from uncharged to positively charged by lowering the pH (e.g., MEP HyperCel). Finally, hydroxyapatite has a more complex mixed mode function due to its positively charged calcium ions and negatively charged phosphate groups.

Preferably, mixed mode resins that exhibit ionic and hydrophobic functionality are utilized, such as Bakerbond ABx (j.t. baker), Capto MMC, captoaphere (ge healthcare), PPA HyperCel, or MEP HyperCel (Pall Corporation). More preferably, a mixed mode chromatography resin MEP HyperCel is used.

The mixed mode chromatography resin MEP HyperCel is characterized as follows:

mixed mode chromatography resins (MEP HyperCel) containing 4-mercapto-ethyl-pyridine as the ligand can be equilibrated with a buffer (e.g., PBS, pH 7.4 or 50mM Tris-HCl, pH 8) having a pH of about 6.5 to 9.9.

For elution of the immunoglobulin of interest from mixed mode chromatography resins (MEP HyperCel) containing 4-mercapto-ethyl-pyridine as ligand, an elution buffer is applied. Preferably, the elution buffer has a pH that disrupts the interaction between the immunoglobulin of interest and the MEP HyperCel column. Preferably, the elution buffer has a pH in the range of from about pH3 to about pH 7, preferably from about pH3.5 to about pH 6, more preferably from about pH4 to about pH 5.5. Arginine (0.1 to 1.0M, 0.2 to 0.8M, 0.4 to 0.6M) may be added to an elution buffer (e.g., MEP HyperCel elution buffer) to reduce immunoglobulin aggregation and prevent loss of solubility at acidic pH.

The advantage of mixed mode chromatography is that resin bound immunoglobulins do not require the addition of large amounts of salts (such as ammonium sulphate) as is the case, for example, when using conventional hydrophobic interaction chromatography.

Mild elution conditions for mixed mode chromatography (e.g., mixed mode chromatography using resins containing 4-mercapto-ethyl-pyridine as the ligand) can reduce aggregation and can preserve the biological activity of the immunoglobulin.

Mixed mode chromatography resins can be regenerated with 10 to 200mM citric acid, 10mM HCl, 0.5 to 1.0M NaOH, 6M guanidine hydrochloride, 2 to 8M urea, or 40% propanol. Preferably, by applying a pre-wash step, the mixed mode chromatography resin can be simply regenerated with 100mM citric acid followed by 0.5 to 1.0M NaOH.

(b) exposing the flow-through obtained in step (a) to mixed mode chromatography, wherein the immunoglobulin is bound to a mixed mode chromatography resin, and obtaining the immunoglobulin in the eluate by eluting the protein from the mixed mode chromatography resin, wherein the ligand is 4-mercapto-ethyl-pyridine;

(a) exposing the sample to strong anion exchange chromatography to obtain immunoglobulins in the flow-through that do not bind to the strong anion exchange chromatography resin, wherein the ligand is-N (CH)₃)₃ ⁺；

(b2) exposing the flow-through obtained in step (b) to protein a affinity chromatography, wherein the immunoglobulin binds to the protein a affinity chromatography resin, obtaining the immunoglobulin in the eluate by eluting the protein from the protein a affinity chromatography resin;

(c) exposing the eluate obtained in step (b2), or a composition derived therefrom and obtained after one or more further processing steps performed after step (b2), to cation exchange chromatography, wherein the immunoglobulin is bound to the cation exchange chromatography resin, and obtaining the immunoglobulin in the eluate by eluting the protein from the cation exchange chromatography resin.

Preferably, for mixed mode chromatography of step (b), a mixed mode chromatography resin comprising a negatively charged ligand may be used. More preferably, the resin comprising the negatively charged ligand is a multimodal weak cation exchanger (Capto MMC) having the formula:

the multimode weak cation exchanger Capto MMC is characterized as follows:

binding load/ml chromatography Medium >45mg BSA/ml Medium at 30mS/cm2)

For elution of the immunoglobulin of interest from the multimodal weak cation exchange chromatography resin, the pH and/or salt concentration of the buffer may be increased. Preferably, both pH and salt concentration may be increased. The salt concentration of the elution buffer may range from 0.25M to 1.75M, preferably from 0.5M to 1M. Exemplary salts/buffers for elution may be sodium phosphate, Tris-HCl, NaCl and/or NH₄And (4) Cl. The ionic strength may be in the range of 0.02-0.3M. The pH of the buffer may be between pH 6 and pH 9, preferably between pH 7 and 8, more preferably an additional washing step with a pH between 5.5 and 7.5 is applied before elution.

In an alternative embodiment, another refinement step may be utilized. The further purification step may be any chromatographic method suitable for use in a purification step, such as anion exchange chromatography, cation exchange chromatography, hydrophobic interaction chromatography or mixed mode chromatography.

(b) exposing the flow-through obtained in step (a) to mixed mode chromatography, wherein the immunoglobulin binds to a mixed mode chromatography resin and the immunoglobulin is obtained in the eluate by eluting the protein from the mixed mode chromatography resin, wherein the ligand of the mixed mode chromatography resin is negatively charged;

(c) exposing the eluate obtained in step (b2), or a composition derived therefrom and obtained after one or more further processing steps performed after step (b2), to cation exchange chromatography, wherein the immunoglobulin is bound to the cation exchange chromatography resin, obtaining the immunoglobulin in the eluate by eluting the protein from the cation exchange chromatography resin;

wherein the ligand of the mixed mode chromatography resin of step (b) has the following formula:

cation exchange chromatography as a refining step

Cation exchange chromatography relies on charge-charge interactions between proteins in a sample and charges immobilized on a resin. In cation exchange chromatography, the molecules to be bound are positively charged, while the immobilized functional groups (ligands) are negatively charged. Commonly used cation exchange resins are S resin (sulfonic acid), SP resin (sulfopropyl), SE resin (sulfoethyl) and CM resin (carboxymethyl).

In general, however, the cation exchange chromatography step can be carried out with all customary commercially available cation exchange resins or membranes. The cation exchange resin may be used in the form of a pre-packed column or a membrane having a functional group (e.g., sulfonic acid) immobilized thereon. Alternatively, the resin may be purchased as a raw material and loaded into the column by the user. With respect to the capacity and size of the column, there is no particular limitation except for the conventional one. The skilled person will know the amount of cation exchange resin to be used and the size of the column. Depending on the overall scale of the process.

Typical commercially available products include, for example, Macro-Prep High S, Macro-Prep CM, Unopshere Rapid S40, Nuvia S and Nuvia HR-S (Bio-Rad, California, USA), Toyopearl CM, Toyopearl SP and Toyopearl GigaCap S (Tosoh Bioscience, Germany), Millipore ProRes S, Fractogel EMD COO-, Fractogel EMD SO3- (Merck KGaA, Germany), Biosepra CM Sepharose HyperD, Biosepra S Sepharose HyperD, S Hyperplug (Pall corporation, New York, USA), Poros HS, Poros XS (Biolipsite, Pro), Poros XS SP 30, Pro, Biophys Sepharose SP, Pro-SP, Biophys Sepharose SP, Pro SP, Biophys Sepharose SP, Biophys Sepharose SP, Biophys SP, Sep Sepharose SP, Sep Sp 63S, Pro, Biophys SP, Biophy, germany). Typically, cation exchange chromatography is performed with a buffer having a pH between 4 and 7.

Preferred cation exchange resins of the present invention are strong cation exchangers using sulfonic acid or sulfopropyl ligands. Most preferred is the attachment of sulfonic acid or sulfopropyl groups to a rigid matrix, such as highly cross-linked agarose, e.g., Nuvia HR-S, or poly (styrene divinylbenzene), e.g., Poros50 HS.

The cation exchanger Poros50HS is characterized as follows:

an alternative preferred material for Poros50HS is Nuvia HR-S, which is a strong cation exchanger based on sulfonic acid groups and a highly cross-linked agarose matrix.

Cation exchange chromatography may be equilibrated with a buffer having a pH of about pH4 to about pH 8. The buffer concentration may be in the range of 10mM to 100mM, preferably in the range of 20mM to 50 mM.

Examples of buffers used for cation exchange chromatography are citric acid, lactic acid, formic acid, succinic acid, acetic acid, malonic acid, glycine, MES, phosphoric acid, HEPES, or mixtures thereof.

The cation exchange chromatography step can separate charge variants of immunoglobulins and can remove residual host cell proteins, aggregates and leached protein a.

Immunoglobulins can bind to the resin at pH values below the isoelectric point (pI) of the immunoglobulin and at low conductivities.

For elution, an increase in the ionic strength of the elution buffer provided by a single stage or gradient may be used. Exemplary salts for elution for cation exchange chromatography are NaCl, KCl, sulfate, phosphate, formate or acetate. Preferably, NaCl or KCl is used. The ionic strength can be increased up to 1M.

Alternatively, an increase in elution buffer pH provided by a single stage or gradient may be used.

A preferred embodiment for performing cation exchange chromatography is a pH working range between 4 and 6, more preferably between 4.5 and 5.5. Carbonic acid (most preferably citric acid) may be used as a buffering substance.

In another preferred embodiment, elution of the immunoglobulin bound to the cation exchange resin is performed by changing the pH value (i.e. increasing the pH). This can be achieved by a gradient from low to high pH provided by mixing two different buffer solutions. Preferably, a citrate buffer is used for low pH and a phosphate buffer is used for high pH. In the most preferred embodiment, the pH gradient is formed by mixing a citrate buffer at about pH 5 to 6 with a phosphate buffer at about pH 7 to 9. The buffer may be formulated with a sodium salt of an acid at a concentration of 10 to 50 mM.

Alternatively, elution may be performed with an increase in both the pH and ionic strength of the elution buffer provided by a single stage or gradient.

The cation exchange chromatography resin can be regenerated with 1M NaCl from 3 to 5 column volumes. Furthermore, an in-place cleaning method comprising the following steps may be applied: (a) washing with 1 to 5 column volumes of 1M NaOH and 1M NaCl; (b) washing with 1 to 5 column volumes of 1M acetic acid or TFA; (c) and (4) rebalancing.

(c) exposing the eluate obtained in step (b), or a composition derived therefrom and obtained after one or more further processing steps performed after step (b), to cation exchange chromatography, wherein the immunoglobulin is bound to a cation exchange chromatography resin, and obtaining the immunoglobulin in the eluate by eluting the protein from the cation exchange chromatography resin, wherein the ligand of the cation exchange chromatography resin is a sulfopropyl group.

In another embodiment, the precleaning step of the invention is followed by mixed mode chromatography in binding mode, followed by protein/peptide affinity chromatography in binding mode.

In another embodiment, the precleaning step of the invention is followed by mixed mode chromatography in binding mode, followed by protein a affinity chromatography in binding mode.

Details regarding protein a affinity chromatography are provided above, and are also applicable to protein a chromatography following mixed mode chromatography.

Details regarding immunoglobulin-binding protein/peptide affinity chromatography are provided above, and are also applicable to protein a affinity chromatography following mixed mode chromatography.

Mixed mode chromatography as an additional refining step

(c) exposing the eluate obtained in step (b), or a composition derived therefrom and obtained after one or more further processing steps performed after step (b), to cation exchange chromatography, wherein the immunoglobulin is bound to the cation exchange chromatography resin, obtaining the immunoglobulin in the eluate by eluting the protein from the cation exchange chromatography resin;

(d) exposing the eluate obtained in step (c) to mixed mode chromatography, wherein the immunoglobulin binds to the mixed mode chromatography resin and the immunoglobulin is obtained in the eluate by eluting the protein from the mixed mode chromatography resin.

(d) exposing the eluate obtained in step (c) to mixed mode chromatography to obtain immunoglobulins in the flow-through that do not bind to the mixed mode chromatography resin.

(d) exposing the eluate obtained in step (c) to mixed mode chromatography, wherein the immunoglobulin is bound to a mixed mode chromatography resin and the immunoglobulin is obtained in the eluate by eluting the protein from the mixed mode chromatography resin, wherein the ligand of the mixed mode chromatography resin is a multimodal strong anion exchanger.

(d) exposing the eluate obtained in step (c) to mixed mode chromatography to obtain immunoglobulins that do not bind to the mixed mode chromatography resin in the flow-through, wherein the ligand of the mixed mode chromatography resin is a multimodal strong anion exchanger.

(a) exposing the sample to anion exchange chromatography to obtain immunoglobulins in the flow-through that do not bind to the anion exchange chromatography resin, wherein the ligand of the anion exchange chromatography is-N (CH)₃)₃ ⁺；

(b) Exposing the flow-through obtained in step (a) to protein a affinity chromatography, wherein the immunoglobulin binds to a protein a affinity chromatography resin, the immunoglobulin being obtained in the eluate by eluting the protein from the protein a affinity chromatography resin, wherein the ligand of the protein a affinity chromatography resin is an alkali stable protein a derivative;

(c) exposing the eluate obtained in step (b), or a composition derived therefrom and obtained after one or more further processing steps performed after step (b), to cation exchange chromatography, wherein the immunoglobulin is bound to a cation exchange chromatography resin, and obtaining the immunoglobulin in the eluate by eluting the protein from the cation exchange chromatography resin, wherein the ligand of the cation exchange chromatography is a sulfopropyl group;

(d) exposing the eluate obtained in step (c) to mixed mode chromatography to obtain immunoglobulins that do not bind to the mixed mode chromatography medium in the flow-through, wherein the ligand of the mixed mode chromatography resin is a multimodal strong anion exchanger.

Media known as mixed mode media or resins are chromatographic media having functional groups comprising charged hydrophobic ion exchange ligands or crystalline minerals such as hydroxyapatite. The term "multimodal chromatography" or "hydrophobic charge induction chromatography" is sometimes used in place of "mixed mode chromatography". Mixed mode chromatography is generally an interplay of at least two principles: hydrophobic interaction and ion exchange or metal affinity interaction and ion exchange. Mixed mode chromatography offers less predictable selectivity, which cannot be reproduced by single mode chromatography methods such as ion exchange or hydrophobic interaction chromatography, respectively. The positively charged hydrophobic ligands belong to a group of mixed anion exchange modes (e.g. Capto MMC) and the negatively charged ligands belong to mixed cation exchange modes (e.g. captoaphere). Some mixed mode resins have zwitterionic character (e.g., Bakerbond ABx). Other mixed mode media have hydrophobic ligands that can be ionized and converted from uncharged to positively charged by lowering the pH (e.g., MEP HyperCel). Finally, hydroxyapatite has a more complex mixed mode function due to its positively charged calcium ions and negatively charged phosphate groups.

Preferably, the mixed mode chromatography step following cation exchange chromatography is performed with a medium comprising a positively charged ligand. More preferably, the positively charged ligand is N-benzyl-N-methylethanolamine having the formula:

(e.g., captoaphere from GE Healthcare, germany).

The characteristics of the mixed mode chromatography resin CaptoAdhere are as follows:

stability of pH

The following conditions may be applied when loading the mixed mode chromatography resin in the bind end elute mode: pH 6 to pH 9, preferably pH 7.0 to 8.5; conductivity from 0.5 to 10mS/cm, preferably from 1 to 4 mS/cm. One or more washing steps may be used. The conditions depend on the pI of the immunoglobulin.

Preferred loading conditions for CaptoAdhere chromatography may be as follows: the resin was equilibrated with 0.5M sodium phosphate pH 8.2 followed by 20mM sodium phosphate pH 8.2. The sample (cation exchange library) was adjusted to pH 8.0-8.5 and conductivity 1-4mS/cm and loaded onto the column. After washing with equilibration buffer 20mM sodium phosphate pH 8.2, the immunoglobulin of interest can be eluted from the CaptoAdher resin with, for example, 20mM sodium phosphate pH 5 to 7, preferably pH 5.5 to 6.5.

In flow-through mode, the pH and ionic strength must be adjusted in such a way that the immunoglobulins do not bind to the mixed mode ligand, while the residual contaminants to be eliminated (DNA, aggregates, leached protein a, host cell proteins) remain bound. The conditions depend on the pI of the immunoglobulin. Preferably, a phosphate or Tris buffer is used in the pH range of 6.5 to 8.5, more preferably between pH 7 and 8. The conductivity is adjusted with salt (e.g. NaCl) or by buffer concentration. Most preferred is a sodium phosphate buffer in the concentration range of 10 to 50mM supplemented with NaCl in the concentration range of 50 to 200 mM. It must be considered that, although desorbing ionic interactions, high salt concentrations promote hydrophobic interactions. In a preferred method, the eluate from the cation exchange chromatography is adjusted to pH 7.5 to 8 and conductivity is increased to 10-12mS/cm with NaCl.

Regeneration (clean-in-place) of mixed mode resins can be performed with low pH, high salt and high pH, for example with 10 to 200mM citric acid, 0.5-2M NaCl and 10mM to 1M NaOH.

The preferred regeneration process is carried out by successive washes with solutions a-D: solution A: 100mM citric acid, 2M NaCl; solution B: 2M NaCl; solution C: 1M NaOH; solution D: 10mM NaOH. The preservation of the resin can be carried out in solution D.

(a) exposing the sample to anion exchange chromatography to obtain immunoglobulins in the flow-through which do not bind to the anion exchange chromatography resin, wherein the ligand of the anion exchange chromatography is–N(CH₃)₃ ⁺；

(d) exposing the eluate obtained in step (c) to mixed mode chromatography, wherein the immunoglobulin is bound to a mixed mode chromatography resin and the immunoglobulin is obtained in the eluate by eluting the protein from the mixed mode chromatography resin, wherein the ligand of the mixed mode chromatography resin is N-benzyl-N-methylethanolamine.

As a purification step, other types of chromatography may also be utilized. For example, anion exchange column chromatography and anion exchange membrane chromatography, which are the most preferred flow-through modes, can be utilized as the purification step.

The isoelectric point or pI of a protein refers to the pH at which the protein has a total net charge equal to zero, i.e., the pH at which the protein has an equal number of positive and negative charges. The determination of the pI can be achieved according to established techniques in the art, such as isoelectric focusing.

In another embodiment, the purification may comprise one or more centrifugation steps prior to the first chromatography step.

In another embodiment, the purification may comprise one or more filtration steps prior to the first chromatography step. In another preferred embodiment, the purification may comprise one centrifugation step and one or more filtration steps. In a preferred embodiment, the first chromatography step is preceded by a depth filtration and microfiltration step. In a more preferred embodiment, the first chromatography step is preceded by a cell separation step, a depth filtration step and a microfiltration step.

(i) centrifuging the sample, wherein the immunoglobulin is obtained in the supernatant;

(ii) (ii) depth filtration of the supernatant obtained in step (i), wherein the immunoglobulin is obtained in the filtrate;

(iii) (iii) microfiltration of the immunoglobulin obtained in step (ii), wherein the immunoglobulin is obtained in the filtrate;

(a) (iv) exposing the filtrate of step (iii) to anion exchange chromatography to obtain immunoglobulins in the flow-through that do not bind to the anion exchange chromatography resin;

Deep filtration

In addition, the process of the present invention may comprise one or more depth filtration steps. Unlike membrane filtration, which separates by trapping particles on the membrane surface, deep filters comprise a matrix of fibers or globules, wherein separation occurs through the matrix rather than on its surface.

Examples of depth filters include, but are not limited to, SXLP700416 and SXLPDE2408SP capsule filters (Pall Corporation), Millistak + XOHC, FOHC, DOHC, AlHC, and BlHC Pod filters (EMD Millipore), or Zeta 20Plus 30ZA/60ZA, 60ZN90ZA, delipid, VR07, and VR05 filters (3M).

Preferably, the depth filter comprises a pre-extraction inorganic filter aid which imparts a strong positive charge to the filter matrix, cellulose and a resin system, such as Zeta Plus from 3M in the uk.

The most preferred depth filters for use in the present invention are the PDE2 and P700 series of capsule filters from Pall Corporation.

Ultra-filtration, virus filtration, micro-filtration

Furthermore, the process of the present invention may comprise one or more microfiltration, ultrafiltration and/or nanofiltration steps. Ultrafiltration is a form of membrane filtration in which hydrostatic pressure forces fluid through a semi-permeable membrane. High molecular weight suspended solids and solutes are retained, while water and low molecular weight solutes pass through the membrane. Ultrafiltration is a process commonly used to separate, purify, and concentrate macromolecular solutions, particularly protein solutions. Ultrafiltration may be combined with diafiltration. This mode is suitable for buffer exchange, removing salts and other microscopic species from solution by repeated and sequential dilutions and reconcentrations. Ultrafiltration can be performed in a tangential flow or cross-flow filtration system (TFF or TF-UF) with a membrane stack, in particular for treating large volumes of sample. Alternatively, ultrafiltration is often performed using hollow fiber systems. The membrane cut-off size is in the range from about 1 to 300 kD. For immunoglobulins, typical cut-offs of ultrafiltration membranes are 10-100 kD. Within the framework of the present invention, UF membranes with molecular weight cut-offs of 30 or 50kD are preferred.

Microfiltration is a particle filtration process using membranes with pore sizes from about 0.1 to 10 μm. For sterile filtration, which imposes special requirements on the environment, sterile microfilters with a pore size of about 0.2 μm are used. The use of additional pre-filters with larger pore sizes (0.45 μm, 3 μm) is common. This prevents the flow rate from decreasing due to rapid clogging of the small pore filter.

Finally, nanofiltration is used primarily for viral filtration in biopharmaceutical production, which is required for the safety of therapeutic proteins produced in mammalian cell cultures. The nanofiltration step is typically performed near the end of the downstream process of filling the purified immunoglobulin stock solution. The pore size of the frequently used nanofilters is in the range from 15 to 35nm (Planova, Asahi Kasei, Japan; or Viresolve, EMD-Millipore, Germany).

In a preferred embodiment of the invention, the purification process comprises one or more ultrafiltration/diafiltration and/or nanofiltration steps. These filtration steps can be carried out using commercially available filtration devices such as those available from Pall Corporation, GE Healthcare, EMD-Millipore or Sartorius.

In another embodiment, the method comprises the further step of incubating the eluate of the protein a affinity chromatography at a low pH of 2.5 to 4.5, preferably pH3 to 4, for a determined time (preferably 30 to 90 minutes).

In another embodiment, the method comprises the further step of incubating the eluate of the mixed mode chromatography at a low pH of 2.5 to 4.5, preferably pH3 to 4, for a determined time (preferably 30 to 90 minutes).

In another embodiment, the method comprises exposing the eluate obtained from the cation exchange chromatography step or a composition derived therefrom and obtained after one or more further treatment steps performed after the cation exchange chromatography step to nanofiltration. Preferably, nanofiltration may be performed with a filter having a pore size of 15 to 35nm, most preferably 20 nm.

For viruses, the flow-through mode anion exchange chromatography step can result in a log of at least 5, at least 5.5, at least 6, at least 6.5₁₀The factor is reduced.

For enveloped viruses, the step of incubating the eluate (obtained from the protein A affinity chromatography step or mixed mode chromatography step) at low pH may result in a log of at least 5, preferably at least 5.5₁₀The factor is reduced.

For enveloped viruses, the cation exchange chromatography step can result in a log of at least 5₁₀The factor is reduced.

The nanofiltration step may result in a log of at least 4 of the enveloped viruses₁₀Log of at least 5 of reduction factor and/or non-enveloped virus₁₀The factor is reduced.

For enveloped viruses, the steps of cation exchange chromatography step and low pH incubation of the eluate (obtained from either the protein A affinity chromatography step or mixed mode chromatography step) may result in a log of at least 10₁₀The factor is reduced.

For enveloped viruses, an anion exchange chromatography step and low pH incubation of the eluate (from a protein A affinity chromatography step or mixed mode chromatography)Step (iii) can result in a cumulative log of at least 10, preferably at least 11, more preferably at least 12₁₀The factor is reduced.

For enveloped viruses, the anion exchange chromatography step, the step of incubating the eluate (obtained from the protein a affinity chromatography step or mixed mode chromatography step) at low pH and the nanofiltration step may result in a cumulative log of at least 15, preferably at least 16₁₀The factor is reduced.

For enveloped viruses, the anion exchange chromatography step, the step of incubating the eluate (obtained from the protein a affinity chromatography step or mixed mode chromatography step) at low pH and the cation exchange chromatography step may result in a cumulative log of at least 15, preferably at least 16, more preferably at least 17₁₀The factor is reduced.

For enveloped viruses, an anion exchange chromatography step, a step of low pH incubation of the eluate (obtained from a protein a affinity chromatography step or mixed mode chromatography step), a cation exchange chromatography step and a nanofiltration step may result in a cumulative log of at least 20, preferably at least 21₁₀The factor is reduced.

For non-enveloped viruses, the anion exchange chromatography step, the cation exchange chromatography step and the nanofiltration step may result in a cumulative log of at least 12, preferably at least 13₁₀The factor is reduced.

A particular embodiment relates to a method for purifying an immunoglobulin from a sample comprising the immunoglobulin and at least one impurity, the method comprising the following steps in the following order:

(c) incubating the eluate obtained in step (b) at a low pH of 2.5 to 4.5 for a determined time;

wherein for enveloped viruses, the method results in cumulative log of steps (a) and (c)₁₀The reduction factor is at least 10.

Another embodiment relates to a method for purifying an immunoglobulin from a sample comprising the immunoglobulin and at least one impurity, the method comprising the following steps in the following order:

(d) exposing the eluate after incubation of step (c) or a composition derived therefrom and obtained after one or more further processing steps performed after step (c) to nanofiltration;

wherein for non-enveloped viruses, the method results in cumulative log of steps (a) and (d)₁₀A reduction factor of at least 10, and/or wherein the method results in a cumulative log of steps (a), (c) and (d) for non-enveloped viruses and/or enveloped viruses₁₀The reduction factor is at least 15.

(c2) exposing the eluate obtained in step (c) or a composition derived therefrom and obtained after one or more further processing steps performed after step (c) to cation exchange chromatography, wherein the immunoglobulin is bound to the cation exchange chromatography resin, obtaining the immunoglobulin in the eluate by eluting the protein from the cation exchange chromatography resin;

wherein for enveloped viruses, the method results in a cumulative log10 reduction factor of at least 15 for steps (a), (c) and (c 2).

(d) exposing the eluate after the incubation of step (c2) or a composition derived therefrom and obtained after one or more further treatment steps performed after step (c2) to nanofiltration;

wherein the method results in a cumulative log10 reduction factor for steps (a), (c) and (c2) of at least 15 for enveloped viruses, and/or a cumulative log10 reduction factor for steps (a), (c2) and (d) of at least 20 for enveloped viruses, and/or a cumulative log10 reduction factor for steps (a), (c2) and (d) of at least 12 for non-enveloped viruses.

exposing the eluate obtained in step (b), or a composition derived therefrom and obtained after one or more further treatment steps carried out after step (b), to nanofiltration;

wherein the method results in a cumulative log10 reduction factor of at least 10 for enveloped and/or non-enveloped viruses of steps a) and b).

(c2) exposing the eluate obtained in step (b), or a composition derived therefrom and obtained after one or more further processing steps performed after step (b), to cation exchange chromatography, wherein the immunoglobulin is bound to the cation exchange chromatography resin, obtaining the immunoglobulin in the eluate by eluting the protein from the cation exchange chromatography resin;

exposing the eluate obtained in step (c2) or a composition derived therefrom and obtained after one or more further treatment steps performed after step (c2) to nanofiltration;

wherein the method results in a cumulative log10 reduction factor of at least 15 for enveloped viruses for steps (a), (c2) and (d), and/or wherein the method results in a cumulative log10 reduction factor of at least 13 for non-enveloped viruses for steps (a), (c2) and (d).

The above methods are also useful for increasing viral safety in immunoglobulin manufacturing processes.

The term "defined time" of incubation as referred to herein means at least 30 minutes, at least 40 minutes, at least 50 minutes, at least 60 minutes of incubation, preferably means from 30 minutes to 90 minutes, more preferably from 45 minutes to 75 minutes, most preferably 60 minutes of incubation.

The pH of the "incubation at low pH" step refers not only to a pH of 2.5 to 4.5, but also to a pH of 3 to 4, preferably 3.25 to 3.75, more preferably to a pH of 3.5.

The term "enveloped virus" refers to any virus having a lipoprotein envelope surrounding a viral nucleoprotein core, such as herpesviruses, cytoviruses (cytoviruses), poxviruses, arenaviruses, arteriviruses, hepadnaviruses, flaviviruses, togaviruses, coronaviruses, orthomyxoviruses, paramyxoviruses, rhabdoviruses, bunyaviruses, filoviruses, baculoviruses, iridoviruses, and retroviruses, including the human pathogen and the model virus murine leukemia virus (MuLV) used in this experiment.

The term "non-enveloped virus" refers to any virus lacking a viral envelope, such as adenovirus, cauliflower mosaic virus, myovirus, algae DNA virus, overlay virus, papova virus, circovirus, parvovirus, birrna virus, reovirus, astrovirus, calicivirus, picornavirus, potyvirus, Tobamavirus, carnauba potyvirus, Anellovirus, and hepatitis e virus, including the human pathogen and the model virus murine parvovirus (MVM) used in this experiment.

The calculation of the virus titer in the starting material and in the relevant product fractions defines the reduction in virus, called log₁₀Reduction Factor (LRF), log₁₀Reduction Value (LRV) or sometimes log₁₀And (4) clearing. LRF calculation methods are listed in the relevant guidelines for virus clearance studies (e.g., EMA guidelines CPMP/BWP/268/95(1996) appendix II "Note for identification on virus identification endpoints: the design, distribution and interpretation of identification of the inactivation and removal of viruses").

A "washing step" is a step performed after the sample is loaded onto the chromatography column but before the protein is eluted from the column. The washing step additionally removes contaminants that weakly or non-specifically bind the matrix, immunoglobulin and/or ligand without significant elution of the immunoglobulin of interest from the resin. In the washing step, the resin is washed with the desired wash buffer (e.g., the wash buffer is passed through the chromatography column until the UV absorbance measured at the column outlet returns to baseline).

The term "elution" is understood to mean the process of desorbing the immunoglobulin of interest from the chromatography resin by changing the solution conditions such that the buffer component competes with the molecule of interest for ligand sites on the chromatography resin. Another elution mode occurs, for example, in affinity chromatography using protein a. In this case, the elution buffer may change the conformation of the ligand or immunoglobulin, thereby relaxing the binding. The immunoglobulin of interest can be eluted from the ion exchange resin by changing the ionic strength of the buffer surrounding the ion exchange material such that the buffer ions in the mobile phase compete with the molecules for charged ionic sites of the ion exchange resin. Alternatively, a change in pH affects the amphipathic protein, so an increase in pH above the pI of the protein prevents it from binding to the cation exchange resin, allowing the protein to elute. The same effect occurs on anion exchange chromatography resins when the pH drops below the pI of the protein.

As understood herein, the term "elution" includes isocratic elution, single-step elution, and gradient elution with or without a preceding elution step. Elution of the immunoglobulin of interest can be performed by increasing the ionic strength or conductivity in the mobile phase by increasing the salt concentration in the buffer solution. Alternatively, an increase or decrease in pH may be suitable. Discrete graded gradients, linear gradients, non-linear gradients or suitable combinations of such gradients may be utilized.

Suitable buffers for washing and for elution may be selected from the group consisting of acetic acid, citric acid, Tris/HCl, Tris/acetic acid, phosphoric acid, succinic acid, malonic acid, MES, HEPES, Bistris, glycine and other suitable buffers to which a salt (such as phosphate, sulfate or chloride, e.g., NaCl or KCl) is added. The ionic strength and salt concentration with which elution is achieved depends on the pH of the buffer solution and the pI of the protein. The wash buffer may further comprise a detergent (e.g., polysorbate), a solvent (e.g., hexylene glycol, isopropanol, or ethanol), or a polymer (e.g., polyethylene glycol). Furthermore, the wash buffer may comprise a chaotropic agent (e.g. urea or arginine) and/or a protease inhibitor (e.g. EDTA).

The term "buffer" as used herein refers to a solution that resists changes in pH by the action of an acid-base conjugate component.

The terms "immunoglobulin" and "antibody" are used interchangeably herein. The immunoglobulin may be a monoclonal antibody, a polyclonal antibody, a multispecific antibody (e.g., bispecific antibody), and fragments thereof that exhibit the desired antigen binding activity. Naturally occurring antibodies are molecules with different structures. For example, a native IgG antibody is a heterotetrameric glycoprotein of about 150,000 daltons consisting of two identical light chains and two identical heavy chains linked by disulfide bonds. From N-terminus to C-terminus, each heavy chain has a variable region (VH) (also known as a variable heavy chain domain or heavy chain variable domain) followed by three or four constant domains (CH1, CH2, CH3 and optionally CH 4). Similarly, from N-terminus to C-terminus, each light chain has a variable region (VL) (also known as a variable light chain domain or light chain variable domain) followed by a constant light Chain (CL) domain. Light chains can be assigned to one of two types, called kappa and lambda, depending on the amino acid sequence of their constant domains.

An "antibody fragment" comprises a portion of a full-length antibody, typically the antigen-binding or variable region thereof. Examples of antibody fragments include Fab, Fab ', F (ab')2, and Fv fragments; a single chain antibody molecule; a diabody; a linear antibody; and multispecific antibodies formed from antibody fragments.

Preferably, the immunoglobulin is a monoclonal antibody. The term "monoclonal antibody" as used herein refers to an antibody obtained from a population of substantially homogeneous antibodies, i.e., the individual antibodies comprising the population are identical except for possible naturally occurring mutations that may be present in small amounts. Unlike conventional (polyclonal) antibody preparations, which typically contain different antibodies directed against different determinants (epitopes), each monoclonal antibody is directed against a single determinant on the antigen. The modifier "monoclonal" indicates the character of the antibody as being obtained from a substantially homogeneous population of antibodies, and is not to be construed as requiring production of the antibody by any particular method.

The immunoglobulin may belong to the murine classes IgG1, IgG2a, IgG2b, IgM, IgA, IgD or IgE, the human classes IgG1, IgG2, IgG3, IgG4, IgM, IgA1, IgA2, IgD or IgE, or combinations or fragments thereof.

The immunoglobulin may recognize any one or combination of proteins including, but not limited to, the following antigens: CD2, CD3, CD4, CD8, CD11a, CD14, CD18, CD20, CD22, CD23, CD25, CD33, CD40, CD44, CD52, CD80(B7.1), CD86(B7.2), CD147, CD152, IL-la, IL-1 β, IL-1, IL-2, IL-3, IL-7, IL-4, IL-5, IL-8, IL-10, IL-12, IL-23, IL-2 receptor, IL-4 receptor, IL-6 receptor, IL-12 receptor, IL-13 receptor, IL-18 receptor subunit, PDGF- β, and its analogs, PLGF, VEGF, TGF- β 2, TGF-p1, EGF receptor, PLGF receptor, VEGF receptor, platelet receptor gpllpIIb/PD, thrombopoietin receptor IIIIb, apoptosis-1 receptor, growth factor, gamma interferon, bone protection protein ligand, interferon, gamma-gamma receptor, B lymphocyte stimulator BLyS, T cell activation modulator CTLA-4, C5 complement, IgE, tumor antigen CA125, tumor antigen MUC1, PEM antigen, ErbB2/HER-2, a tumor-associated epitope present at elevated levels in the serum of a patient, a cancer-associated epitope or protein expressed on breast, colon, squamous cells, prostate, pancreatic, lung and/or renal cancer cells and/or on melanoma, glioma or neuroblastoma cells, tumor necrosis core, integrin α 4 β 7, integrin VLA-4, B2 integrin, α 4 β 1 and α 4 β 7 integrins, TRAIL receptor 1, 2, 3 and 4, RANK ligand (KL), TNF- α, adhesion molecule VAP-1, epidermal cell adhesion molecule (EpCAM), intercellular adhesion molecule-3 (ICAM-3), Leukocyte integrin (leukointetgrin) adhesin, platelet glycoprotein gp IIb/IIIa, cardiac myosin heavy chain, parathyroid hormone, sclerostin (sclerostin), MHC I, carcinoembryonic antigen (CEA), alpha-fetoprotein (AFP), Tumor Necrosis Factor (TNF), Fc-y-1 receptor, HLA-DR 10 β, HLA-DR antigen, L-selectin, and IFN- γ.

The immunoglobulin may be, for example, alemtuzumab (affeimumab), abciximab (abciximab), adalimumab (adalimumab), alemtuzumab (alemtuzumab), alemtuzumab (arcitumomab), belimumab (belimumab), canakinumab, cetuximab (cetuximab), dinomab (denosumab), trastuzumab (trastuzumab), infliximab (imcirumab), carpromab (capromab), infliximab (infliximab), ipilimumab (ipilimumab), alemtuzumab (abciximab), rituximab (rituximab), basiliximab (basiliximab), palivizumab (basiliximab), rituximab (CD-25 (rituximab), rituximab (CD-e), rituximab (CD-e (rituximab), rituximab (CD-3 (rituximab), rituximab (CD-e, rituximab (rituximab), rituximab (e, rituximab (rituximab), rituximab (e, rituximab), rituximab (e, rituximab), rituximab (e, rit, obinutuzumab, panitumumab (panitumumab), pertuzumab (pertuzumab), ranibizumab (ranibizumab), romosozumab (tomosozumab), tositumomab (tocilizumab), tositumomab (tositumomab), clenoliximab (clenoliximab), keliximab (keliximab), galiximab, formalirumab, lexatuzumab, bevacizumab (bevacizumab), and vedolizumab.

The immunoglobulin of the invention is preferably an IgG molecule, such as an IgG1, IgG2, IgG3 or IgG4 molecule. More preferably, the immunoglobulin is IgG 1. Even more preferably, the immunoglobulin is IgG1, wherein at least the Fc portion is human. The immunoglobulin may be a murine-human chimeric IgG1 in which the Fc portion of IgG1 is human. Most preferably, the chimeric immunoglobulin is rituximab or infliximab.

Rituximab is a chimeric anti-cd 20 antibody, which is described in detail, for example, in WO 9411026.

Infliximab is a chimeric anti-TNF α antibody, which is described in detail in, for example, WO 9216553.

The immunoglobulin may be a humanized IgG1 form of a murine progenitor antibody. Most preferably, the humanized antibody is trastuzumab or bevacizumab.

Trastuzumab is a humanized anti-HER 2 antibody, which is described in detail in, e.g., WO 9222653.

Bevacizumab is a humanized anti-VEGF antibody, which is described in detail in, for example, WO 9845331.

The immunoglobulin may be a fully human IgG1 antibody. Most preferably, the human antibody is adalimumab or denosumab.

Adalimumab is a human anti-TNF α antibody, which is described in detail in, for example, WO 9729131.

Denosumab is a human anti-RANKL antibody, which is described in detail in, for example, WO 03002713.

In one embodiment, the antibody may be rituximab or adalimumab.

Monoclonal antibodies herein expressly include "chimeric" antibodies (immunoglobulins) in which a portion of the heavy and/or light chain is identical with or homologous to corresponding sequences in antibodies derived from a particular species or belonging to a particular antibody class or subclass, and the remainder of one or more chains is identical with or homologous to corresponding sequences in antibodies derived from another species or belonging to another antibody class or subclass, as well as fragments of such antibodies, so long as they exhibit the desired biological activity.

In addition, the monoclonal antibodies herein also include "humanized" antibodies. Such antibodies are obtained by "humanizing" non-human (e.g., murine) antibodies, containing only minimal sequences derived from animal immunoglobulins. The majority of the molecule is human sequence. The residues from a hypervariable region of a human acceptor antibody are substituted with residues from a hypervariable region of a non-human donor antibody having the desired binding characteristics.

Finally, the monoclonal antibodies herein also include fully human antibodies, which can be obtained by screening a human antibody library.

In a preferred embodiment, the sample is derived from cell culture supernatant obtained from recombinant CHO cell culture. Preferably, the sample is obtained from a recombinant cell culture in a growth phase.

The chromatographic medium may be disposable or reusable. In one embodiment, the chromatographic medium is reusable.

In particular embodiments, the anion exchange chromatography resin of step (a) is reusable.

Reusable chromatography media is cost effective compared to chromatography media configured as disposable media. Especially for the first pre-wash step, a large amount of chromatography medium is used. Thus, it is particularly advantageous to use a reusable chromatography medium (e.g., a reusable anion exchange chromatography resin for the precleaning step).

The term "reusable" as used herein means that the media or resin is configured to be reused for more than one purification cycle, i.e., at least 2, 5, 10, 50, 100, 200, 300, 400, 500 or more purification cycles. Between each cycle, the chromatographic medium or resin may be washed and/or regenerated and/or preserved.

In another embodiment, the chromatography medium of all chromatography steps is reusable.

The term "substrate" or "solid phase" refers to a non-aqueous substrate to which the substrate can adhere. The substrate of interest herein is typically a substrate comprising glass, ceramic, silica, cellulose, agarose, methacrylic polymer or polystyrene.

"ligand" refers to any functional group that interacts with a protein or with at least one contaminant and covalently binds to a "substrate".

"resin" refers to any chromatography material in the form of beads comprising a matrix with binding functional groups (ligands) that can interact with proteins or at least one impurity. One exception is gel chromatography resins for size exclusion chromatography, which generally do not contain any attachment ligands. The resin may be provided as pellets of different sizes and packed in a column. Alternatively, pre-packed columns may be purchased.

The method of the invention can be used for immunoglobulin purification on a small scale and on a large scale. Preferably, the process is carried out on a large scale.

"Small-scale" is also denoted "laboratory-scale" and refers to the purification of a sample comprising less than 50g of immunoglobulin, less than 10g of immunoglobulin or less than 1g of immunoglobulin. "Small-scale" also refers to a purification process in which less than 50g immunoglobulin, less than 10g immunoglobulin or less than 1g immunoglobulin is eluted from the column of the capture step.

"Large Scale," also referred to as "production scale" or "manufacturing scale," refers to the purification of samples comprising more than 50g of immunoglobulin, more than 100g of immunoglobulin, more than 200g of immunoglobulin, or more than 300g of immunoglobulin. "Large Scale" also refers to a purification process in which more than 50g of immunoglobulin, more than 100g of immunoglobulin, more than 200g of immunoglobulin, or more than 300g of immunoglobulin is eluted from the column of the capture step.

Examples

The method for purifying immunoglobulins according to the present invention is supported and illustrated by reference to the following examples. It must be emphasized that these examples should in no way be interpreted as limiting the scope of the invention.

Example 1: immunoglobulins and cell cultures

The methods of the invention are not dependent on the particular antibody nor the particular host cell used to express the immunoglobulin. The same is true for the expression pattern and the selected culture conditions optimized for maximum yield in the harvest. Different monoclonal antibodies were used during the development of the method of the invention. They were successfully purified on various scales according to the process of the present invention. Most of the selected experiments presented in the tables were performed with the mouse-human chimeric anti-CD 20IgG1 antibody rituximab. In addition, some other experiments were performed with the fully human anti-TNF α IgG1 antibody adalimumab. Both antibodies were expressed recombinantly in CHO cells propagated in fed-batch culture at different scales. Experiments in the development phase were mainly performed with harvest broth from a 100L laboratory scale. The production scale and maximum culture volume used in the examples was 1000L. Unless otherwise indicated, scale always refers to the culture volume.

Example 2: cell culture fluid harvesting and pre-wash filtration steps

The following process is described for a 100L scale. Cells and cell debris were removed by separation with a LAPX404 separator (Alfa Laval) at 9600 rpm at a flow rate of 100L/hr. The separated culture broth was filtered continuously through the following filters (Pall Corporation): (i) capsule filter SXLP700416 SP; (ii) the capsule filter SXLPDE2408 SP; and (iii) again through the capsule filter SXLPDE2408 SP. Both depth filtration and microfiltration principles are achieved by this filter arrangement. The filtered broth was also microfiltered using a Sartopore 2/0.2 μm membrane filtration device (Sartorius) prior to the first chromatography step.

Example 3: selection of chromatography resins (tables 1 and 2)

A relatively large series of commonly used and potentially useful process chromatography resins from different suppliers were tested for their effectiveness as pre-wash steps, capture steps and polishing steps in a wide range of screening programs (see fig. 2A and 2C). This was done during the early development phase of the invention. The resin was packed in a small column (10-20ml) and samples containing rituximab were taken from a 100L laboratory scale, either directly after separation and filtration (pre-wash step and capture step) or from the protein a eluate (purification step of binding mode). The protein A and the cation exchange chromatography library obtained after the precleaning chromatography were used for the purification step in flow-through mode. For chromatographic operation

The Purifier System (GE Healthcare).

Pre-cleaning resin: eight different anion exchange chromatography resins were tested and compared in flow-through mode. These resins are Capto Q, Q-Sepharose FF, Unopshere Q, Nuvia Q, Fractogel TMAE, Poros HQ, Q HyperCel and Toyopearl Super Q650. The column was equilibrated packed with 10mM Tris-HCl, pH 8.0. The test criteria were: (i) maximum loading based on the volume of sample passed before contaminant breakthrough; (ii) regeneration (including fading); and (iii) the extent of precipitation after acidifying the collected flow-through below pH 5.0. Four resins were found to be most suitable for the precleaning step (table 1), which gave similar results except for Nuvia Q. However, Nuvia Q clearly proved to be the better and is the preferred resin (table 2).

Affinity capture chromatography resin with protein a: a total of nine different protein a resins were tested and compared in binding and elution mode without the use of a washing step. The same conditions were used with respect to column size, flow rate and retention time. The column equilibration buffer was 40mM sodium phosphate, 150mM NaCl, pH 7.4. Elution was performed with 100mM sodium citrate, pH 3.5. The resins tested were MabSelect, MabSelect Xtra, MabSelect SuRe LX, Ulospere Supra, ProSep Ultra Plus, Protein A Ceramic hyper F, Poros MabApture A, and Toyopearl rProtein A. The criteria are: (i) dynamic and specific binding capacity (breakthrough assay); (ii) the desired regeneration method; (iii) sensitivity to harsh cleaning (NaOH, urea, Gu-HCl); (iv) purity of the eluate (residual HCP, leached protein a); and (v) cost calculations. In summary, three resins were found to be superior and most useful (table 1). Poros mabchoice a and two MabSelect SuRe resins from GE Healthcare are the most promising candidates for large scale processes. Mabscapure a had 15% lower HCP removal capacity than MabSelect SuRe and was the second choice. The most preferred resin is MabSelect SuRe LX, which has slightly higher binding loading than MabSelect SuRe (table 2).

Non-affinity capture chromatography resin: a total of five different resins were tested in this category. These resins are Capto MMC (Mixed mode), Capto S (cation exchanger), MEP HyperCel (mixed mode), PPA HyperCel (mixed mode) and Toyopearl AF Red (dye ligand based on Procion Red HE-3B). The criteria are: (i) dynamic and specific binding capacity (breakthrough assay); (ii) the desired elution standard; (iii) regeneration method (0.5M NaOH); and (iv) eluate purity (HCP). All these resins (table 1) showed effective capture capacity but different purification capacity. HCPs in the eluate differed in mass and quantity. The non-affinity capture step may be applied prior to subsequent protein a affinity chromatography (see fig. 2B), and then essentially functions as a second pre-wash step to further de-load the valuable protein a column. However, both mixed mode resin results showed better and could also be used as capture step in the downstream sequence lacking any protein a affinity step (see figure 2C). These promising resins are Capto MMC and MEP HyperCel (table 2).

Resin for binding mode purification chromatography: this category considers only cation exchangers, except for a mixed mode chromatography resin. A large number of (n ═ 14) common cation exchangers were tested: poros HS, Poros XS, SP Sepharose HP, Capto SP impros, YMC BioPro30S, YMC BioPro 70S, Unopshere Rapid S40, Nuvia S, Nuvia HR-S, Toyopearl SP 650S, Toyopearl GigaCap S650S, Millipore ProRes S, and Fractogel EMD SO₃. The column was loaded with a protein a (MabSelect SuRe) eluate containing rituximab and low amounts of contaminants, adjusted to a protein concentration of 10mg/ml with equilibration buffer. Not all resins were tested to the same extent. In addition to the dynamic and specific binding capacity (breakthrough assay), the ability to separate residual HCP and product-related impurities (aggregates, undesired charge variants) was also examined. Elution is performed with increasing salt and/or pH gradient. The resins show significant differences with respect to the separation of impurities in the acidic (charge variants) and basic (aggregate) fractions. This criterion is weighted as it is the intended purpose of the immunoglobulin refining step. A total of six resins were found to be suitable for the refining step (table 1). In Poros50HS, SP Sepharose HP, Capto SP Impres, Nuvia HR-S, Toyopearl SP 650S and Fractogel EMD SO3, the cation exchanger Poros HS 50 from Applied Biosystems and Nuvia HR-S, a resin from Bio-Rad, showed the best removal potential for contaminants HCP, aggregates, undesired charge variants and leached protein A. In addition, the positively charged mixed mode resin captoaphere from GE Healthcare was examined for its usefulness as a binding mode refining step. The same samples, column sizes and standards were applied in the same way as the cation exchangers. The equilibration buffer was 20mM sodium phosphate, pH 8.2, sample pH was adjusted to 8.2 with NaOH, and further diluted with equilibration buffer. Although the resin is capable of binding higher amounts, an effective separation of rituximab requires a loading of 20-23 mg/ml. Elution of bound protein was performed with 20mM sodium phosphate, pH 6.0. The CaptoAdhere resin in bound mode showed very promising removal of contaminants, which was chosen as the preferred resin for the refining step (table 2).

Resin for non-binding mode purification chromatography: in this category, only anion exchangers and one mixed mode resin are considered. A total of seven different common anion exchangers were tested: poros HQ, Capto Q, Unopshere Q, Nuvia Q, Toyopearl GigaCap Q650, Q HyperCel, and Fractogel EMD TMAE. The criteria are: maximum purity of rituximab in the obtained flow-through is of particular interest for residual aggregates, HCDNA and HCP. The column was loaded with a cation exchanger (Poros HS) library after protein a (MabSelect SuRe) step. Three anion exchange chromatography resins Poros HQ, Capto Q and Nuvia Q were found to be best suited for the flow-through mode of the purification step (table 1). In addition, the positively charged mixed mode resin captoaphere from GE Healthcare was examined for its usefulness as a flow-through mode refining step. The same samples, column sizes and standards were applied in the same way as the anion exchanger. The equilibration buffer was 20mM sodium phosphate, 100mM NaCl, pH 7.8. CaptoAdhere resin also showed significant removal of contaminants in flow-through mode and was slightly superior to anion exchange chromatography resin. This is easily explained by the additional hydrophobic interaction that complements the anion exchange function. Therefore, CaptoAdhere was chosen as the preferred resin for the flow-through mode refining step (table 2).

Table 1: process resins suitable for use as a precleaning, trapping and polishing chromatography step [ AEX ═ anion exchange chromatography; CEX ═ cation exchange chromatography; MMC ═ mixed mode chromatography ]:

a suitable resin; + + ═ preferred resins

Table 2: preferred chromatography resins [ AEX ═ anion exchange chromatography; CEX ═ cation exchange chromatography; MMC ═ mixed mode chromatography ]:

process step	Resin composition	Type (B)	Ligands	Suppliers of goods
					Pre-cleaning	Nuvia Q	AEX	Trimethylammonium salts	Bio-Rad
Capture	MabSelect SuRe LX	Affinity	Alkali-stable protein A derivatives	GE Healthcare
					Capture	MEP HyperCel	MMC	4-mercapto-ethyl-pyridine	Pall Corporation
Capture	Capto MMC	MMC	Multimodal weak cation exchangers	GE Healthcare
					Refining	Poros 50HS	CEX	Sulfopropyl radical	Applied Biosystems
Refining	Nuvia HR-S	CEX	Sulfonic acid	Bio-Rad
					Refining	CaptoAdhere	MMC	N-benzyl-N-methylethanolamine	GE Healthcare

Example 4: pre-wash anion exchange chromatography step

As shown in FIGS. 2A-CThe free sequence purified on a 100L scale (rituximab or adalimumab) and a 1000L scale (rituximab). The preferred resin for the precleaning chromatography step is Nuvia Q, which is carried out in flow-through mode. This process step was carried out using the broth obtained after the pre-wash filtration procedure described in example 2. The pre-wash chromatography was performed in flow-through mode with Nuvia Q anion exchange chromatography resin to reduce the impurity loading (HCP, HCDNA, aggregates, lipids, pigments, etc.) of the subsequent capture step. The resin-packed column (size 60cm diameter x16cm bed height for 1000L scale, packing volume about 45L; size 14cm diameter x27cm bed height for 100L scale, packing volume about 4.1L) was equilibrated with WFI (2CV), 1M Tris-acetate pH 6.0(3CV) and 20mM Tris-acetate pH 7.2(4CV) in succession. The product solution was passed through the column (17g/L resin) at a flow rate of about 200 cm/hr, and then WFI (2CV) was passed through the column. By sequential application of (i)40mM NaH₂PO₄Regeneration of the Nuvia Q resin was performed by back washing with 10mM EDTA, 2M urea, 1.5M NaCl, pH 7.2(4CV), (ii)100mM citric acid, 2M NaCl (10CV), (iii) WFI (4CV), (iv)1M NaOH (4CV), and (v)10mM NaOH (2 CV). The column was then stored in 10mM NaOH solution.

Example 5: effect of Pre-Wash anion exchange chromatography step on the reuse of MEP HyperCel as Capture resin (Table 3)

MEP HyperCel is the preferred non-affinity resin for the capture step, which can be applied to large scale processes with (FIG. 2B) or without (FIG. 2C) a subsequent protein A affinity step. Contamination (fouling) of the MEP HyperCel column was found to be severely insufficient. However, this can be prevented or strongly reduced by applying a pre-wash anion exchange column (Nuvia Q in this example). Without the Nuvia Q precleaned column, repeated use of MEP HyperCel required a vigorous, durable, and expensive regeneration procedure, even though the lifetime was limited. The experiments of table 2 were performed with small model columns (20ml) packed with Nuvia Q and MEP HyperCel, respectively. The loading and performance of the Nuvia Q chromatography was as described in example 4. Flow-through was immediately loaded onto MEP HyperCel without adjustment. At the same time, the second capture column was loaded directly with the culture broth of example 2, i.e. the Nuvia Q step was bypassed. The trap column was loaded until maximum loading was reached and product appeared in the flow-through (breakthrough). Bound IgG was eluted from the MEP HyperCel column by pH reduction (pH 4). The binding loading was calculated from the volume before breakthrough. The mixed mode resin was simply regenerated and rebalanced for the next run. Regeneration of MEP Hypercel was performed in countercurrent by passing 100mM citric acid solution followed by 1M NaOH. The contact time with NaOH was 60 minutes, then the column was prepared for the next use by re-equilibration and complete removal of NaOH (pH control). The Nuvia Q column was regenerated as described in example 4. A total of eight cycles (seven recycles) were performed. The results are summarized in table 3 and support the superiority of the Nuvia Q procedure. The binding capacity was unchanged when Nuvia Q precleaning was applied. In contrast, without this step, the bound loading decreased from run to run, down to 64% after eight cycles.

Table 3: effect of flow-through anion exchange chromatography (AEX) as a Pre-washing step on the reuse of the Mixed mode resin MEP HyperCel used as a Capture step (IgG binding Capacity per ml resin)

Number of cycles	MEP HyperCel	AEX→MEP HyperCel
			1	16.5mg/ml	16.1mg/ml
2	13.2mg/ml	16.0mg/ml
			3	12.6mg/ml	15.9mg/ml
4	11.9mg/ml	16.2mg/ml
			5	11.5mg/ml	16.1mg/ml
6	11.0mg/ml	15.9mg/ml
			7	10.7mg/ml	16.0mg/ml
8	10.5mg/ml	15.9mg/ml

Example 6: capto MMC capture chromatography

Capto MMC resin is a negatively charged mixed mode chromatography medium (see table 2) applied in the downstream sequence shown in the process flow scheme of fig. 2B (five column process) and fig. 2C (four column process). In these sequences, Capto MMC essentially acts as a second pre-wash step to purify the sample and remove key contaminants, such as proteases, that can damage subsequent protein a affinity chromatography resins. Furthermore, this step allows significant sample concentration, thus reducing the processing time for protein a chromatography. Capto MMC chromatography was performed in binding mode, loaded with the Nuvia Q flow-through described in example 4, which was adjusted to pH 5 with acetic acid. Rituximab was purified according to this method on both 100L and 1000L scale. The column size for the 1000L scale was 60cm diameter x15cm bed height (packing volume about 42L) and the column size for the 100L scale was 20x14cm (packing volume about 4.4L). The column was equilibrated with 20mM sodium acetate, pH 5.0, and the column with bound rituximab was washed with 40mM sodium phosphate, pH 6.5. Elution was optimized for maximum recovery and was performed with 40mM sodium phosphate, 250mM NaCl, pH 7.5. The flow rate was 150-200 cm/h. The eluate was directly applied to a protein a column.

Example 7: protein A capture chromatography

Protein A capture chromatography was performed with either MabSelect Sure (100L scale) or MabSelect Sure LX (1000L). The process parameters were the same except for the scale of the column. Samples were taken after the method applied in example 4 (process of figure 2A, Nuvia Q flow-through) or after the method applied in example 6 (process of figure 2B, Capto MMC eluate). The column size for the 1000L scale was 40cm diameter x30cm bed height (packing volume about 38L) and for the 100L scale was 20x10.4cm (packing volume about 3.2L). The protein A column was equilibrated with 40mM sodium phosphate, 150mM NaCl, pH 7.4. Unless otherwise stated, the product solutions were loaded at 20g protein/L resin (100L scale) or 35g protein/L resin (1000L scale). The column was washed with equilibration buffer (2CV), then with 40mM sodium phosphate, 1.5M NaCl, 2M urea, 10mM EDTA, pH 7.4. Elution was performed with 100mM sodium citrate, pH 3.5. The flow rate was 140 cm/hour. Regeneration of the Mabselect Sure or Mabselect Sure LX resin was performed by sequential back washing with (i)0.2M NaOH (2CV), (ii) WFI (2CV), 3.5% acetic acid, 100mM sodium sulfate (2CV), and (iii) WFI (2 CV). The reequilibration column was used for the next run or stored in 20% ethanol.

Example 8: effect of Pre-Wash anion exchange chromatography on leached protein A (Table 4)

To examine the effect of prewash chromatography (Nuvia Q) and temperature on protein a (MabSelect SuRe LX) leaching, a series of experiments were performed in a scale-down protein a affinity chromatography. The column used had a volume of 12 ml. By using

The Purifier System (GE Healthcare) performs a chromatographic run. Sample (I)Is a small sample taken from a 1000L batch of rituximab. Samples were taken from process steps obtained after the procedure described in example 2 (before the Nuvia Q precleaning step) or after the procedure described in example 3 (after the Nuvia Q precleaning step). Protein a affinity chromatography was performed as in example 7. The column was loaded with 25-30mg protein/ml resin. The sample and protein A affinity chromatography are maintained at room temperature (20-25 ℃) or placed in a cold room (2-8 ℃). Two parallel samples were taken from two different aliquots, purified and tested in parallel. The results are shown in table 4. The average of two parallel leaching runs at room temperature without a preceding Nuvia Q step was 23.4ng/mg (protein a equivalents per mg IgG). The effect of the precleaning step was evident (table 4). At room temperature, when the sample was passed through a Nuvia Q column before the protein a step, only 9.1ng/mg (═ 39%) of leaching occurred. This effect is also observed at low temperatures which themselves have a significant effect on leaching. The average leaching without Nuvia Q was 5.0ng/mg and the average leaching with Nuvia Q was 3.4ng/mg (68%) (Table 4). The Nuvia Q step significantly reduces protein a leaching and allows the use of room temperature which is more preferred for the affinity chromatography step. The capture of proteolytic activity of the bound Nuvia Q resin best explains the effect of Nuvia Q on protein a leaching.

Table 4: the effect of the prewash anion exchange (Nuvia Q) chromatography step on leached protein a (from MabSelect SuRe LX) measured in protein a eluate. Two parallel chromatographies were performed at two different temperatures.

Example 9: pre-wash and capture columns in series

Since the Nuvia Q precleaning anion exchange step was performed in flow-through mode, a subsequent protein a affinity resin (MabSelect SuRe LX) was able to efficiently capture immunoglobulins from this flow-through, it was possible to directly connect the Nuvia Q column in series with the MabSelect SuRe LX column. The downstream process summarized in fig. 2A and 2B was run from a 1000L scale (rituximab) with this serial precleaning and capture column. However, unless otherwise stated, 100L scale processes are also carried out using series columns. The two columns are balanced separately and then switched in connection by a valve. The product solution was loaded at about 100L/hr (1000L scale) or about 10L/hr (100L scale) onto the column in series in the upstream direction described for Nuvia Q in example 4. After washing with WFI (2CV), the Nuvia Q column was split by valve switching on the chromatography equipment and regenerated in countercurrent as described in example 4. Additional processing of the protein a column (i.e., washing, elution, and regeneration) was performed with the split configuration described in example 7.

Example 10: inactivation of viruses

As shown in fig. 1 and 2, the virus inactivation step occurs after protein a affinity chromatography. Elution with low pH from the affinity matrix was used. In this aqueous acidic environment, many viruses, especially enveloped types of viruses, are unstable and disintegrate. The protein a method developed for the present invention produced an eluate with a ph of 3.5 (see example 7). Similarly, the eluate of mixed mode capture columns (MEP HyperCel or Capto MMC) has a low pH4 (see examples 5 and 6). Inactivation of MabSelect SuRe LX eluate (1000L scale, rituximab) is described later. The monoclonal antibody eluted from the protein a column was in 100mM sodium citrate pH3.5 and directly entered virus inactivation tank a. The eluate was diluted approximately 2-fold with WFI directly in tank a. The pH of the solution was controlled, readjusted to 3.5 with 100mM citric acid as needed, and then transferred to virus inactivation tank B where the solution was stirred at 20-24 ℃ for 60 minutes at 65 rpm. The pH of the solution was then adjusted to pH 4.5 with 50mM NaOH to provide starting conditions for the subsequent cation exchange chromatography step.

Example 11: poros50HS cation exchange chromatography (fine 1)

Separation of contaminants and product-related substances (e.g., charge variants) is performed by using cation exchange chromatography as the first purification step. This step was included in all purification sequences (100L rituximab and adalimumab, 1000L rituximab). Columns packed with Poros50HS resin (size 60cm diameter x 32cm bed height for 1000L scale, packing volume about 90L; size 25cm diameter x15cm bed height for 100L scale, packing volume about 7.3L) were equilibrated with (i) WFI (water for injection, 2CV) and (ii)20mM sodium citrate pH 5.5(4CV) in succession. The product solution obtained after virus inactivation and sample conditioning (pH 4.5) as described in example 10 was loaded onto a column at about 8g protein/L resin, thereby passing through a 0.45 μm Kleenpak Nova prefilter (Pall Corporation). The column was washed with WFI (1CV) and then subjected to gradient elution. The gradient was formed by mixing 20mM sodium citrate pH 5.5 (buffer a) and 40mM sodium phosphate pH 7.8 (buffer B) in the following proportions and order: (i) 100% a (0.2CV), (ii) linear gradient to 40% a + 60% B (2CV), (iii) linear gradient to 100% B (6CV), (iv) 100% B (2 CV). The flow rate was 150 cm/hr. The eluate was split in fractions to allow specific mixing. Regeneration of Poros50HS resin was performed by successive washes with (i)2M NaCl (1CV) and (ii)1M NaOH (2 CV). The column was then stored in 10mM NaOH.

Example 12: CaptoAdhere Mixed mode chromatography (refining 2)

The second purification step is but optional and applies to rituximab on a 100L and 1000L scale. The resin chosen for final chromatography in a process with two purification steps (FIGS. 2A and 2B) was CaptoAdhere, which utilized ligand N-benzyl-N-methylethanolamine. The ligands have positively charged groups and thus provide an anion exchanger function in addition to hydrophobic interactions. Chromatography can further reduce residual trace contaminants such as HCDNA and HCP. Residual leached protein a, product aggregates and product fragments may also be removed by this step. The CaptoAdhere refining step is performed in flow-through mode as well as in binding mode.

CaptoAdhere chromatography in flow-through mode: the sample used for this final chromatography was Poros50HS library after the protocol described in example 11. The dimensions of the packed column were 14cm diameter x13cm bed height for the 1000L scale (packing volume about 2L) and 5x 13cm for the 100L scale (packing volume about 0.2L). The column was equilibrated with 20mM sodium phosphate, 100mM NaCl, pH 7.8. The pH of the mixed fraction was adjusted to 7.8 with 0.2M NaOH and the conductivity was increased to 10-12mS/cm with 1M NaCl. The conditioned pool was passed through a CaptoAdhere column at a load of 250-275g protein/L resin and the entire flow-through was collected. The flow rate was 300 cm/hr. Regeneration of the CaptoAdhere resin was performed by successive washes with (i)100mM citric acid, 2M NaCl (2CV), (ii)2M NaCl (1CV), (iii)1M NaOH (2CV), and (iv)10mM NaOH (2 CV). The column was then stored in 10mM NaOH.

CaptoAdhere chromatography in binding mode: the pH and conductivity of the Poros50HS pool obtained after the procedure described in example 11 were adjusted to pH 8.2 and 3.2mS/cm, respectively. The dimensions of the packed column were 40cm diameter x28cm bed height for the 1000L scale (packing volume about 35L) and 14x 27cm for the 100L scale (packing volume about 4.1L). The resin was equilibrated with 20mM sodium phosphate pH 8.2. The product solution was loaded onto the column at 15-20g protein/L resin. Elution was performed with 20mM sodium phosphate pH 6.0. The flow rate was 300 cm/hr. The column is regenerated as described for the flow-through mode.

Example 13: final filtration step

Between the final chromatography and the final stock solution filled with the drug substance, several filtration steps are required to formulate the selected preservation buffer, fix the desired concentration and remove the virus. The immunoglobulin purification method of the present invention is not dependent on these filtration methods. Thus, the method, apparatus and selected membrane in this example must be understood as being a selection only, with any modifications possible. The process for the 1000L scale for a process with two refining steps is briefly described below.

Tangential flow ultrafiltration/diafiltration (UF/DF) buffer exchange: the eluate from the CaptoAdhere column was collected in the tank of a UF/DF apparatus and concentrated to 8g/L using an Omega Centrasette membrane (Pall Corporation,30kD cut-off). The retentate was diafiltered with 10 volumes of formulation buffer (25mM sodium citrate, 154mM NaCl, pH 6.5).

Removing nanofiltration viruses: nanofiltration is the most demanding and reliable virus removal step, operating on the basis of size exclusion in the nanometer range. The diafiltered product solution was transferred to a removable tank and then subjected to nanofiltration with a Viresolve Pro Modus 1.3 filter (Millipore,20nm pore size). The filter was adjusted with 25mM sodium citrate, 154mM NaCl, pH 6.5 prior to filtering the product solution. To protect the nanofilter, a Sartopore 2midi caps prefilter (Sartorius,0.2 μm pore size) was applied. Filtration is carried out by an overpressure of at most 2 bar.

Concentration and final formulation by tangential flow ultrafiltration/diafiltration (UF/DF): the nanofiltration product solution was collected in the tank of a UF/DF apparatus and concentrated to about 10.2g/L using Omega Centrasette membranes (Pall Corporation,30kD cut-off). The concentrated product solution was transferred to a mobile tank. The jar was placed under a laminar gas flow and tween 80 was added to a final concentration of 0.09% (w/w).

Final microfiltration (sterile filtration): the final microfiltration was performed with a 0.2 μm Mini Kleenpak capsule filter (Pall Corporation).

Example 14: final purity of the batches obtained by different Processes (Table 5)

The results regarding the final purity of the two representative batches produced by the conventional process of fig. 2A (following, for example, Fahrner RL 2001) and the new process of fig. 2B are summarized in table 5. The immunoglobulin was rituximab, purified from 100L scale. The process steps of the conventional purification method (process 1B) include three steps of chromatography: (i) MabSelect SuRe (capture); (ii) poros50HS (binding mode); and (iii) Poros50 HQ (flow through mode). The chromatography sequence of the new process (process 2B) comprises: (i) nuvia Q (pre-wash); (ii) capto MMC (capture); (iii) MabSelect SuRe (middle); (iv) poros50HS (binding mode, refine 1); and (v) CaptoAdhere (flow through mode, refine 2). The individual steps were carried out as described in examples 1, 2, 4, 6, 7 and 10 to 13. The purity parameters selected in table 5 are: (i) relative amount of IgG monomers (%); (ii) residual host cell protein (HCP, ng/mg IgG); and (iii) residual host cell DNA (HCDNA, pg/g IgG). The analytical method is described in example 15 below. As can be seen from all three parameters, the batch purified according to the new process 2B had a higher purity than the batch purified according to the classical process 1B (table 5).

Table 5: comparison of the quality of two purified batches obtained by two different processes (conventional process (1B) and one of the processes of the invention (2B)). "Process 1B" refers to the standard process shown in FIG. 1B without a pre-wash chromatography step. "Process 2B" refers to the process of the invention shown in FIG. 2B, which comprises a pre-wash chromatography step (Nuvia Q flow-through) and a mixed mode chromatography capture step (Capto MMC) followed by protein A (MabSelect Sure). The test method comprises the following steps: size exclusion high performance liquid chromatography (SEC-HPLC), enzyme-linked immunosorbent assay (ELISA), and quantitative polymerase chain reaction (qPCR). The test parameters were percent monomeric IgG, host cell protein per mg IgG (HCP) and host cell dna per g IgG (hcdna).

Test method	Parameter(s)	Process 1B	Process 2B
				SEC-HPLC	Monomer (%)	99.6	99.7
ELISA	HCP(ng/mg)	4.3	1.1
				qPCR	HCDNA(pg/g)	289	142

Example 15: analytical method

Several analytical methods are applied during and at the end of the process to characterize the quality of the purified immunoglobulins. These methods are standard methods and are described in the literature (e.g. european pharmacopoeia). The principles of those methods that produce the results in the tables are briefly described below:

high performance size exclusion chromatography (SEC-HPLC): the SEC-HPLC method is used to determine impurities having a molecular weight different from the molecular weight of the immunoglobulin. Size Exclusion Chromatography (SEC) is a technique based on the separation of molecules based on hydrodynamic diameters proportional to their size. A high performance liquid chromatography system for SEC (SE-HPLC) was used, which has a much better resolution than conventional SEC. Chromatography is performed as described in the literature (e.g. WO2013067301) to quantify immunoglobulins in terms of monomers, dimers, aggregates and fragments. Detection of proteins was based on UV absorbance. Relative purity means the integrated monomer peak area as a percentage of the total area of all peaks. The test results were calculated from the average of the repeated measurements.

Enzyme-linked immunosorbent assay for the quantification of Host Cell Proteins (HCPs): the measurement was performed by a sandwich ELISA method. The CHO host cell proteins bind to specific anti-CHO antibodies immobilized onto the polystyrene surface of a standard 96-well microtest plate, followed by a horseradish peroxidase (HRP) -labeled secondary antibody. The enzymatic reaction is then carried out by adding a 3,3 ', 5, 5' Tetramethylbenzidine (TMB) substrate to the well, which produces a colored product that can be detected by visible light absorbance, depending on the presence of the antibody-peroxidase conjugate. The microplate was read at 450nm (reference wavelength 620 nm).

Enzyme-linked immunosorbent assay (ELISA) for quantitative leaching of protein a: measurements were performed with a commercially available MabSelect Sure Ligand ELISA kit from Repligen. The leached MabSelect Sure ligand binds to a specific anti-protein a rabbit antibody immobilized on the polystyrene surface of a standard 96-well microtiter plate, followed by a biotin-labeled secondary antibody. The presence of bound biotin was detected by incubating the wells with streptavidin-horseradish peroxidase conjugate. The enzymatic reaction is then carried out by adding a 3,3 ', 5, 5' Tetramethylbenzidine (TMB) substrate to the well, which produces a colored product that can be detected by visible light absorbance, depending on the presence of the antibody-peroxidase conjugate. The microplate was read at 450nm (reference wavelength 620 nm). The assay sensitivity was 0.1ng/ml sample.

Quantitative polymerase chain reaction for the quantification of Host Cell DNA (HCDNA)(qPCR): the measurement was performed by a real-time quantitative PCR method based on TaqMan chemistry (Applied Biosystems). The method is very sensitive and specific in detecting DNA contamination. The assay is based on the use of Sequence Specific Primers (SSP) and fluorescently labeled hybridization probes

Sequence-specific amplification and real-time fluorescence detection of well-defined DNA fragments by Polymerase Chain Reaction (PCR) of (1). The entire process (including instrumentation, reagents, sampling and software-based calculations) was performed according to the supplier's instructions. In a PCR reaction, a large amount of double-stranded DNA is synthesized from the initial DNA region determined by specific primers. Reporter dye and quencher dye-labeled oligonucleotide probes bind to the region of the template DNA to be multiplied. During the PCR reaction, the DNA polymerase decomposes the probe, bringing the two dyes into close physical proximity, and the reporter dye emits fluorescence proportional to the synthesis product of the PCR reaction. CHO-specific probes and primers were used for the measurement, which doubled the amount of the appropriate region of CHO host cell DNA. During this step, the fluorescence signal increases, and after a certain number of cycles, the fluorescence exceeds the threshold. This cycle number is proportional to the initial amount of DNA. It is possible to determine the absolute amount of host cell DNA by comparing the number of cycles obtained with the sample to a calibration curve.

Example 16: verification of virus removal and inactivation

Due to concerns regarding viral contamination from raw materials or production steps, the production process of recombinant protein drugs (e.g., monoclonal antibodies) produced by cell culture requires viral removal and/or inactivation. Thus, there are considerable regulatory requirements for the viral safety of each manufacturing process that produces biotherapeutic proteins derived from cell cultures. Downstream processes must be validated for their ability to remove and/or inactivate potential viral contaminants according to existing guidelines from various regulatory authorities, such as the European Medicines Agency (EMA) and the U.S. Food and Drug Administration (FDA). The purpose of the virus clearance study was to demonstrate effective virus removal and inactivation during manufacture as part of the overall safety of recombinant protein drugs from cell culture sources.

Selection of process steps: the downstream processing of the IgG1 antibody rituximab was validated against the selected steps. The process steps analyzed are representative of the scale-down versions of the corresponding large scale steps described in the previous examples. Four process steps are selected:

a) nuvia Q precleaning anion exchange chromatography (see example 4);

b) low pH viral inactivation of protein a eluate (see example 10);

c) poros HS cation exchange chromatography (see example 11);

d) viresolve Pro nanofiltration (see example 13).

Selection of viruses: two commonly used model viruses were selected:

a) murine leukemia virus (MuLV);

b) mouse parvovirus (MVM).

MuLV is a member of the family of Retroviridae (Retroviridae), a single-stranded RNA virus with an envelope, and is about 80-100nm in size. MVM is a member of the Parvoviridae (parsoviridae) which is a non-enveloped single-stranded DNA virus. Parvoviruses are among the smallest viruses known and range in size from 20 to 24 nm. Both viruses were obtained from the American Type Culture Collection (ATCC).

The performance of the experiment: real intermediate process samples from one large-scale batch were stored frozen (< 15 ℃ C.). Aliquots of 20ml were thawed before the experiment and spiked with high virus titre MuLV or MVM, respectively. Process step b) "low pH viral inactivation of protein a eluate" (see example 10) only MuLV was tested. Parvoviruses are known for their resistance to low pH treatments due to the morphology of the naked virus capsid. Therefore, MVM was not tested for low pH incubation. Spiked starting material and treated samples were analyzed quantitatively with infectivity assays and qPCR based on virus-specific cells, and the reduction factor was calculated as log₁₀The value is obtained. All test materials were previously investigated for interference with the assay, and parallel control incubations demonstrated virus stability during the experiment. Infectivity assay detects only infectious virus, whereas qPCR contains both infectious and inactivated virus. For each process step and virusType, duplicate runs were performed. In the case where the treated sample does not contain detectable viral titers, the calculated limit of detection of the assay is taken as the maximum titer. The reduction factor is expressed as at least log₁₀“≥”。

Results of the virus clearance study: the results of a single experiment are shown in table 6 for each run, step and virus. The high reduction factor of the precleaning step based on simple flow-through mode anion exchange chromatography (resin Nuvia Q) is surprising. Log discovery₁₀The reduction factor is at least 6.5 to 6.7 for MuLV and 6.6 for MVM. This step is the best of the four tested. This is unexpected, especially in the case of difficult parvoviral MVMs. Furthermore, by using a combination of a pre-wash anion exchange chromatography and a simple 60 min hold step of the protein a eluate (pH 3.5), a cumulative reduction factor of at least 12.3 can be obtained for enveloped viruses such as MuLV. Total cumulative log₁₀The reduction factor is 21.7 for MuLV and four steps and at least 13.3 for MVM and three steps.

Table 6: log of different process steps for reduction of two model viruses murine leukemia virus (MuLV) and murine parvovirus (MVM)₁₀The factor is reduced. Two runs were performed for each step and virus.

List of references

F.Bules et al, 1991, "Construction and characterization of a functional polymeric human serum-human antibody directed against human serum fragment-D dimer", Eur.J.Biochem.195,235-242

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Claims

1. A method for purifying immunoglobulins from a sample comprising large-scale immunoglobulins and at least one impurity, the method comprising the following steps in the following order:

wherein for enveloped viruses, the method results in cumulative log of steps (a) and (c)₁₀The reduction factor is at least a factor of 10,

wherein the sample is harvested cell culture fluid, cell culture supernatant.

2. A method for increasing viral safety in a large scale immunoglobulin manufacturing process, the method comprising the following steps in the following order:

wherein the sample is harvested cell culture fluid, cell culture supernatant.

3. The method of claim 1 or 2, further comprising the steps of:

wherein for non-enveloped viruses, the method results in cumulative log of steps (a) and (d)₁₀A reduction factor of at least 10, and/or wherein for enveloped viruses, the method results in a cumulative log of steps (a), (c) and (d)₁₀The reduction factor is at least 15.

4. The method of claim 1 or 2, further comprising the steps of:

wherein for enveloped viruses, the method results in a cumulative log10 reduction factor of at least 15 for steps (a), (c), and (c 2).

5. The method of claim 4, further comprising the steps of:

wherein the method results in a cumulative log10 reduction factor of at least 20 for enveloped viruses for steps (a), (c2) and (d) and/or wherein the method results in a cumulative log10 reduction factor of at least 12 for non-enveloped viruses for steps (a), (c2) and (d).

6. The method of claim 1 or 2, wherein the anion exchange chromatography of step (a) is a strong anion chromatography comprising a ligand which is a strong anion exchange chromatography ligand other than a trimethylammonium ethyl group bound to a methacrylic acid polymeric matrix, wherein the ligand is selected from the group consisting of Quaternary Aminoethyl (QAE) moieties, quaternary ammonium moieties and trimethylammonium moieties.

7. The method of claim 1 or 2, wherein large scale refers to samples comprising more than 50g of immunoglobulins.

8. The method of claim 1 or 2, wherein the cell culture supernatant is a pretreated cell culture supernatant.

9. A method according to claim 6, wherein the ligand is trimethylammonium (-N (CH)₃)₃+)。